don't know about your climate, but I just now cut off spent bloom stalks & raggedy leaves, but I didn't cut the stalks all the way back:

I'll do that after the first hard frost turns them to mush, to give the plants as long as possible to store energy & to give myself as much time as possible to look at green leaves instead of brown mush.

I'd keep the ones that are flowering;
it'll be winter soon enough!