What people are actually asking for is a way to forbid Facebook itself from using or copying a post, which any technically- or legally-minded reader would interpret as forbidding Facebook from storing posts at all. Obviously most users don't actually want their account and posts to be deleted, but they're asking for just that, and become angry when Facebook does not comply.
If you are truly upset that a company somewhere is making money by hosting a service that you post your private life to, there are a couple simple solutions:
1) Find some registered non-profit with blog hosting (does this even exist?), and only post there.
2) Host your own site, set a password so only your friends can see it, and only post there.
3) Stop posting your private life online.