Yes, it is possible, it’s just very rare. The reason it’s rare is because it requires an almost megalomaniacal level of determination to know only truth and to live only in truth, above everything else. The road from self-realization to enlightenment is paved with tears.

Self-realization requires ego to surrender to life. That is already very hard for the ego, very painful. Enlightenment requires ego to surrender to death. This is much more painful, much more. In enlightenment, life and death, being and non-being are seen to be one.

But it has always been known that it’s possible, and it has always been known that it’s hard. The notion that it’s impossible mostly comes from modern-day spirituality, a severely watered down version of the “classical” one. That’s why some people say such ridiculous things as, for example, masters such as Osho still have some sort of “egoic shadow” and refuse to accept their “shadow”, and it makes them “spiritual fundamentalists” or something. The people who say that are seeing their own “shadow” in Osho. At least they acknowledge that, but it doesn’t make them true masters, it’s the opposite. It’s just that they like to think that they are, that enlightenment is impossible, hence, every master who says they have no ego is full of shit, and they themselves, of course, are not, because they acknowledge their “shadow”.

This is just make believe. There is no shadow in full light, there cannot be. It just takes much more than people are willing to go through.

Osho spent 3 years in silence immediately after his self-realization event. And he was not even done by then. When he was studying for his PhD in philosophy, he was still very sleepy all the time, he talks about it, that means the unfolding of the dream continued. Maharishi spent 6 years in the trance state following his “first death” (self-realization), not talking to anyone except known masters, before he experienced what was described as his “second death” (enlightenment). That’s actually an overstatement, enlightenment is very unpronounced compared to self-realization, it’s almost a non-event, but that’s not the point that I’m trying to make. The point is that neither of them started to teach before the unfolding was more or less complete. Who does this these days?

Think about it this way. If there is truth and there are falsehoods, how is it possible that it would be impossible to completely get rid of falsehoods and see only truth? That is a very convenient position for the ego to take, sure, but it’s an absolutely absurd position from the definition of “truth”.

The key point to remember in this process is that it starts with you and it ends with you. That it’s all about you. All of it. The whole thing is about you. Not about consciousness, not about God, not about compassion, and even though you will experience all that in spades, ultimately it’s all about you. And it is most definitely, most certainly not about other people, although you will experience it also. Only you. If you never lose track of that (which is, unfortunately, very easy), you will keep going, because falsehoods hurt you and truth liberates you. If you do lose track of that, you will get stuck.

If you haven’t attained self-realization yet, this should be your only goal. Do not read the rest of this answer. It is not for you. There are multiple methods to attain self-realization, and they have all been described in the literature ad nauseam, so I won’t describe it here. The only method that hasn’t been described, and, unfortunately, has much prejudice against, is psychedelics, and I will probably describe it sometime in the future. It’s a dangerous method (not physically, but with regards to how easily one could fall into somewhat delusional states), but if one understands psychedelics and knows how to use them, it’s a good method, just as good as any. There is no person on the planet that became worse off psychologically because of the responsible use of psychedelics - they are a very good tool. Here’s one answer of mine on the topic: Artem Boytsov’s answer to How do psychedelics cause hallucinations? Why are they said to be more intense when your eyes are closed?

If you did attain self-realization, then methods and practice become harder, because your mind is always in a more or less meditative state, and meditation can do little for you unless you meditate for very long, for example, spend 3 years in silence, like Osho. The intention to know the full truth, and the belief that the full truth can be known (or, to be more accurate, that all falsehoods can be dropped - the truth is simply what’s left) is the most important thing. There are, however, things that you can do which will be productive or non-productive, and I will list them here.

One thing to understand about this list is that ego is a social creature. It is not your body, it is merely the part of your brain which is concerned with how it is seen by other people (or yourself). It is also the part of your brain which sees other people as psychological entities distinct from your own. Ego cannot exist in isolation, ego can only exist in society - in isolation it has nothing to stand on. Which is why enlightenment is a jump into complete aloneness, not physical, but psychological aloneness, which is also complete wholeness and the opposite of loneliness, because the concept of loneliness is no longer applicable here.

So, things that are non-productive, that is, that will make the process of unfolding go slower:

Assigning any kind of blame or even causation for your emotions. Any answer to any question of the sort of “Why am I experiencing this emotional response?” leads to more dreaming, more explanation, more stories. The only question one should ask himself is “What?”, never “Why?”. What am I experiencing? And it’s not even a question to be asked in the mind, it’s just an intention and allowance to feel whatever is experienced fully and completely, without giving it any explanation whatsoever. In other words, acceptance. Feeling through, without suppression, but without expression either (tears do not count as expression, but any kind of emotional engagement with the person does). You can express yourself later when the emotion is no longer there. First work through it, then engage.

Engaging in society. If, after your self-realization you become so naked, vulnerable and bare emotionally that engaging with other people brings you all sorts of stuff like tears, anger, pain, etc. then it might actually be productive as long as you’re not expressing them. But this is rare. This basically means that the whole truth was revealed to you in self-realization and you will arrive to full truth whether you want it or not. That was Osho’s experience and that was my experience. If that’s the case, you already know what’s happening and engaging with other people will be the least of your worries - the fear might follow you everywhere until you work through it. The journey will be intense. For most people it’s not the case. Most people merely discover what they say is their “true self” or “higher self” in self-realization (which is also an illusion), and are happy to come back to society relatively quickly, revitalized and enjoying social interactions again and all the emotions they bring, albeit from an elevated perspective. For those people, solitude will be productive because their egos will start to scream and feel very lonely. As Osho said, “suffer the pain of your aloneness”.

Teaching. This is by far the most common mistake people make, and it is so common because self-realization opens up the flood of compassion, which is then quickly used by the ego to build relationships with other egos not based on the petty stuff like it did before, but based on compassion and the desire to help. It’s a beautiful relationship, the highest one, the noble one, but it’s still a relationship, it’s not aloneness yet, not wholeness. Compassion is the hardest thing to work through for most people, it seems endless. It’s actually not. It’s just your own pain and suffering which is attributed to other people and explained and experienced as compassion. Just like all dreaming goes, if this desire is satisfied you will be happy. If it’s not satisfied, you will cry for humanity and your own impotence. This is your own suppressed pain, it’s only interpreted as the pain of others by the ego. There’s nothing wrong with compassion but compassion as an emotional response to others’ suffering actually is counter-effective in teaching, because the student’s ego latches on to the teacher’s ego and they play the game of “oh my woes” and “the poor you”. Very fun for the egos, not good at all for seeing the truth, your own well-being, and the progress of the student. For as long as you like it, you will play it. Staying in solitude will make you miss it and you will cry. As Osho beautifully said (this guy’s a poet, really): “only when you are completely gone you have jewels to share”

Now, the things that are productive, that is, that will make the process of unfolding go faster:

Trying to catch yourself dreaming at night, that is, remembering that what you’re seeing is just a dream, that it’s not real. There are multiple methods for that, they are pretty much equivalent to inducing lucid dreaming, and Osho used to describe them, too. If you are self-realized the dream will probably just disappear. It’s just practice for the mind to stop miring in imagination. Usually, the intention is enough. If you’re still dreaming, just say to yourself every time you go to bed, “I will remember that it’s just a dream”. Don’t get obsessed with it, don’t get upset if it doesn’t seem like it’s working, don’t try to resist dreaming - none of that works. Just say that every night, and in a few months, you will start to slowly remember. First rarely, then more frequently, then some weird things might start to happen to you in your dreams hehehe. It’s all good.

Psychedelics. The relationship with psychedelics changes abruptly after self-realization. Before self-realization you can have great, wonderful, blissful trips. Some people have great experiences on psychedelics without much difficulty. That was just a bait hahaha. It is my experience that after self-realization good trips are, strictly speaking, impossible, and all psychedelics start working pretty much the same way, there is not much difference between them. Whatever pain, tears, fear, sorrow and insanity are still there, whatever beliefs you have about yourself in the remainder of your unconscious will invariably come up, there’s no question. I remember I took two puffs of weed and it was one of the most painful things I have ever done. Yes, there will still be a “good” part of the trip but the increase of well-being there compared to your day-to-day well-being might even be very minor, if you are in a relatively deep state of non-duality. Noticeable, yes, but minor. But the bad stuff, oh, it will be there. So you go through it, cry your tears, have your fears, and then you notice in the next couple of weeks that your day-to-day conscious experience became deeper, emotions became subtler, ego has even less control, dreams became more surface-like, the mind became quieter and bodily sensations became even more rich and wonderful. Same state, just deeper. Not immediately, with time. Give yourself time to integrate it, there’s no rush. What happens during the psychedelic experience itself is inconsequential - it’s just your mind’s crazy imagination, the realizations and deepening happen afterwards, with time.

So, it’s basically a process of tiring your mind of dreaming (imagining and believing), so that it doesn’t dream anymore. Or, you could say, it’s the process of progressively shedding the layers of the dream like an onion, until only truth remains. Those descriptions are equivalent. In either case, whatever pain, tears, fear are still left in you, are yours to experience and you will experience it all. In complete enlightenment, psychedelics don’t work any more.

Teja said in his answer that you cannot will yourself through this process. He’s right. But you kinda can’t and you can. “Will” in this context simply amounts to how much of your remaining suffering you are willing to take, how fast you want to go down to the center. You are at the driver’s seat (the real you), you’re just not realizing it. There is more peace, beauty and serenity behind every drop of tear, every gust of anger and every wave of fear. It’s all hidden behind suffering. How quickly you want to “eat” it all is entirely up to you. You might as well do absolutely nothing and it will probably all unfold and go away slowly by itself in the next 10–15 years following self-realization. Or it might not. It is actually, on a deep unconscious level, entirely up to you. It’s all about your willingness to surrender, nothing else.

In self-realization, your reality kinda flips. Everything is upside down now. You thought you had consciousness, now you realized you are consciousness and you exist in it. You thought you existed in the world, now the world exists in you. In enlightenment, it flips back again, the world is outside of you again, and you can’t even find consciousness any more, there’s only you, as a whole, indivisible. But the mountains are mountains again, they are not you.

So if you do want “authentic and unexcelled enlightenment”, as Gautama put it, don’t stop until it flips again, just pace yourself according to your ability to take it all. There’s a lot to take, really a lot. More than you probably know. But that’s the fun of it.

When the cup of tea is just a cup of tea to you, you are done. Not a manifestation of consciousness, not an expression of energy, not something unexplainable as in “I can’t honestly tell what it is”, not a perception of your mind, not a part of your dream, not “you” as the undifferentiated subject/object of non-duality, just a cup of tea. Nothing else. A cup of tea.

It will be a very simple, very mundane realization. Somewhat disappointing, even. As it should be.

When that happens you will know that you’re done, and you won’t be asking the question of whether it’s possible to dissolve the ego completely.