My "don't do that" instruction for chickens is to use one of my forefingers to "peck" at their heads. Just a quick tap. (And, out of habit with having dogs forever, I do say "No!" at the same time.) No whole hand & arm movement, if you can avoid it. Just a quick tap like you're pecking them, as any other senior chicken would do.
They are curious animals. Much of their pecking is to check things out, not necessarily to eat it. After all, they don't have hands with which to touch things, pick them up, etc. I think the button pecking and pulling is curiosity, as well as tugging on rings and bracelets or other jewelry. But freckles on your skin could be tasty bugs, lint on your clothing might be a bit of leftover feed.