How do you kill a god?

Hi y'all! So I am brainstorming a story as I am trying to do an outline and the problem I have is "how can my human (no magic at this point) protagonist kill my antagonist whose power is that of a level of a god"?

My antagonist's power is basically controlling weather but not like storm of x-men. Rather, she draws from energy around her and transforms that into power to control weather. I know this is not original and I hope to make this more original as I develop the story.

I read other "david v. Goliath" theme books in fantasy and i noticed most if not all of the davids (human ordinary character) would discover they have "some magic" which then helps them defeat the antagonist. But i was hoping my Protagonist would remain non-magic until the end.

I appreciate any comment from you guys! Thank you!