Which of these marvel abstracts can destroy a multiverse
an infinite multiverse
Galactus, In-Betweener, Chaos and Order, Living Tribunal, Scathan, Molecule Man, Eternity, Multi-Eternity, Death, Oblivion, First Firmament, Logos, Phoenix Force, Chaos King, Mad Jim Jaspers, Legion, Franklin Richards, Marquis of Death
Any Multiversal abstract or above could (I mean, they're meant to be on a Multiversal scale, so...). Maybe Franklin Richards because I think it was stated he could create a Multiverse, but he seems more consistently Universal. Molecule Man put a Multiverse in a box among other stuff, so he should be able to. Chaos King maybe but I've seen debate on if his feats were really just Universal. Phoenix Force is possibly Multiversal off of the scans I've been seeing in the past weeks. Scathan too if we believe Protege's hype.
Multi-Eternity is technically the embodiment of one, and the First Firmament is the embodiment of the Universe that eventually became the Multiverse.
They're the only contenders as far as I'm concerned. But I'm not really convinced they could destroy the Multiverse, or else it wouldn't have made much sense for the First Firmament to imprison Multi-Eternity.