I think it's probably against the site rules asking someone else to actually send you a method, Nembutal is an illegal substance anyway, and I don't think the OP would want to break the law by sending it.
But I do really envy the OP for having N though and yes it's horrible the thought of someone wasting such a peaceful method as I think that to leave this world in such a peaceful way would be the best outcome possible, we are all going to die anyway so I think it would always be preferable to exit peacefully on my own terms, but this is just the way that things are. I also don't understand why the OP would want to get rid of N as existing can very easily get much more unbearable for anyone at any moment, I would see it as being comforting always having the option of a peaceful way to exit.