You can edit old posts, which is tracked. You can't 'delete' accounts or posts via the steemit front end.
Reread my OP --
add a 'delete' function that blots out entries into the STEEM blockchain so it doesn't appear on their front-ends.
I said nothing about "delete from the blockchain", which is an inappropriate use of double quotations, since I never said any such thing.
See pic related when you attempt to open @thedarkoverlord account via steemit front-end -- you can't do this as a normal account. Why not?
My mistake. In that case I agree if Steemit can do it why can't we control our own account?