Taking the literalness of the prefix "omni", it is impossible to destroy an omnipresent. For to be omnipresent is to mean that its existence is in "everything", i.e, that it would still be there after being erased from existence; If it has been erased, it means that after deletion ceased to exist, and if there is some time where it does not exist, then it is not at all, so it is not omnipresent.
We could say that the omnipresent being is even in nothing itself, because if it is in everything, it is also in the previous state the existence of all things. Similarly, it would also mean that he would be there even if you erased everything else, like ideas or concepts.
But, as I say, the omnipresence of fiction isn't true omnipresence, just as the omnipotence of fiction isn't omnipotence either. So if you refer to "omnipresence" as something like "personifying the universe" or something similar, then yes, there are several ways to destroy an omnipresent.
An example of what I mean is the "created" omnipresents. They aren't truly omnipresents, because they weren't there before some higher being created them. This analogy generates an infinite regression where only an omnipotent could have omnipresence. Despite this, it isn't standard for this wiki to take the literality of the omni prefix, so I usually don't even question how this is treated here. In general, it depends on "what" the community where you are considered as "omni".
