You don't have to make demands, people naturally forget little things said in conversations. Facebook remembers verbatim, in a searchable format. It even pushes your post into other people's "timelines" so you don't know who sees it or when. It's no wonder people get skittish, when Facebook gives them so little control over their content.

No it's not. That's bringing even attention to it. You example is more similar to deleting an unliked post, and then posting "Everyone please forget my last post. Just pretend it never happened."

Deleting a post from Facebook/Instagram/etc doesn't delete it from the memory of the people who did see it. It just prevents more people from seeing it, or those people from seeing it again. So it's almost exactly like making an unpopular statement in conversation, and then abruptly changing the subject.