how do i delete stories on snapchat properly?

If the point is keeping one or two people from seeing it, you don't have to delete anything. Settings > View My Story > Custom lets you pick friends to hide it from. Works for anything you post after that too.

open your own story, tap the three dots on the individual snap, and delete is on there — it's per snap, not the whole story. only stops new views though. anyone who already watched it has watched it, and if memories is set to save automatically there's a second copy sitting in there to clear as well.