Stuff like daylilies, if cut down now, will start sprouting again; and possibly be up to full growth height by mid October, greatly diminishing next year’s flower production because all the posy juice was used up growing a bunch of leaves. Let these die back until brown, and then you will find that these dead leaves and old flower stems will pull out easily.
Hostas too; just let them die back until dead and you will find that the withered up leaves will separate from the crown effortlessly. No tuggin and yankin and running the risk of pulling them up roots and all.
I would snip off the Coneflower and Black-eyed-Susan petalless flower heads now to keep them from spreading their seed all over the place. You could probably cut the whole plant down to the ground; they shouldn’t come back anymore this year.
The long and short of it is, “if it’s green let it be, if it’s brown cut it down”.