@ElAleph,
I'm new here, so bear with me. :-)
Personally, I believe that God is omnipotent because he 1) he knows absolutely EVERYTHING that has ever happened, and 2) he is omniscient, and therefore able to learn everything new that happens as it happens, allowing him to remain all-knowing even though he created the universe with physical properties such as the uncertainty principle and free will, which prevent him from just predicting the "outcome" of the universe at the moment he creates it.
So, then, if he knows everything, all the decisions he makes should be to further the increase of knowledge in the universe, allowing him to increase his own knowledge, because he simply remained the same for all of eternity, why bother existing?
And if his purpose in existence is to collect new knowledge and, in a sense, "expand" himself, it becomes a question not of whether God
can commit suicide, but
why he would ever want to, as it would defeat the purpose of his existence, and, furthermore, end it.
So in answer to the OP's question, I would think God would certainly have the means to do such a thing, but not the motive.
And another thing, if God possesses absolute knowledge of everything, then couldn't he be said to "define" the universe in a sense; were this "definition" gone from the universe and absolute knowledge and perfection made unattainable, what would be the purpose of
our existence?