Bernkastel
Reaper of Miracles
Erasing a Galaxy is irrelevent, she has the power to manipulate probability, then she managed to absorb Chaos himself, with the abilities she gained from that she gained the ability to alter reality itself. The House of M storyline in the comics culminated in her saying the words "No More Mutants" and all but the original X-men team stopped being mutants (though that was a writer's device to keep some X-men since it sold well, coincidentally this happened at the same time as the movies started to come out)
She can literally say, no more powers or no more sailor moon and reality will alter at her command. She hasn't destroyed any galaxies because she isn't a villain but if she chose to, she could.
She can alter reality Ech, she could make it so that Sailor Moon never even existed.
No it's not. Sailor Moon's soul is connected to the Galaxy Cauldron; every time she dies she'll be reincarnated again and again unless the galaxy itself is destroyed. Scarlet Witch could incapacitate Sailor Cosmos, but she couldn't kill her unless she could erase galaxies.
Irregardless the rules state death or incapacitation, so I'll give you the match. What prize do you want?
SCARLET WITCH CAN NO LONGER BE USED.