Who can destroy a universe?

SC AM still had the potential to bust universes *thanks anti-matter wave*

it just would have taken more time then it did back in his COIE days.

Eternity - Does it instantly
Infinity - Does it instantly
Galactus after devouring his worldship(no UN) - Probably could do it quickly as shown in the fight against the Watcher
SC AM - Hard to say, we never saw his full power. Probably not.
Superman Prime 1M - We have him stating that he could have stopped the Atom's universe from collapsing, but otherwise no real feats. Unknown.
The Tyrant at full power - Probably not
Death - Does it instantly
Trion Juggs - Probably not
All 12 of the guardians working together - Maybe
Cyttorak - Doubtful
Rune King Thor - Maybe he could just make the 5 minute mark
Spectre without backing of presence - Does it instantly
Tiamut(celestial) - Does it instantly
Bat-Mite - Does it instantly
Ion II - Highly doubtful