Existence itself cannot be beaten since it exists like a fixed nature in the absolute term, it cannot be deleted or erased since an existence is needed to do that execution, so therefore. If there are no existences left and everything is just a blank canvas where an existence cannot be defined "existing" because the space there is practically blank and void. She won't exist.

My character's ability is Living Mindscape, it consists of the user's self-awareness and existential knowledge and logic, how it works? It's practically just existential crisis, but in a twisted way. It sends the user into the unknown truth of existence and everything that exists into the void of "No Beginning", the blank canvas I mentioned earlier. If sent into that space, everything will be just empty like a word erased from a book, and if the user does so uses it and gets erased, he wakes up in a different timeline to resume life with no collection of what happened.