I don't think it's even possible to self annihilate, because I don't believe in oneness or unified consciousness. Nevertheless, your description of the Left Hand Path seems interesting. Is there any book or website about this topic that you would recommend?
At the time of your post, Raimo, and my reply, I had not yet come across the writings (and videos) of Kurt Leland. I am currently reading his book, The Multidimensional Human: Practices for Psychic Development and Astral Projection.
He maps the the experience of consciousness as emanating (originally) from the divine "plane" (he refers to the term "plane" as used by the Theosophists) - he also refers to this quite often as "Source."
In my reply, I stated that the view of Dr. Flowers was [paraphrased] "That the Right Hand Path adherent would eventually 'return to Source' which would result in self-annihilation. A Left Hand Path adherent has chosen to retain its identity and thus never submits to 'God' or 'Nature' and thus would never face self-annihilation."
Interestingly, Leland, in The Multidimensional Human, starting at the bottom of page 86 begins to discuss one's evolution through the planes in a "return to Source."
"We're limited to the physical plane if our true identity is weak (which is why we need to develop our existential senses). Accessing the astral plane in dreams means that our identity is stronger. But we're not free to travel into the upper reaches of this plane until we've mastered our emotions.
Once our emotions have been mastered, we're strong enough to explore the lower reaches of the mental plane. Mastering our thoughts allows us to rise to the higher reaches closer to the Source. And so it goes, beyond the mental plane to the buddhic, nirvanic and monadic. On the divine plane, our identity would be strong enough to experience complete union with Source without dissolving." [emphasis mine]
Considering this possibility, it dawned on me that I had not considered this third possibility. Retention of identity while merging (and after merging) with Source, once identity has been established. If Leland is correct, once we establish identity, the only way to return to Source is through a strengthening (mastership) of that identity in relation to all planes and all beings in all planes.
And so before, I only considered an "either, or" situation and had not imagined this third possibility.
As for the possibility of self-annihilation, because I see any limitation as unacceptable (including self-annihilation) I do not wish to believe it isn't possible. Having said that, at the end of the day, I may not ultimately be the one (or at least a one) to make a call like that.
In addition, I can see a philosophical argument that includes the possibility of "self-annihilation" to be... impossible. I am still working on writing it up in a reasonably articulate way.