All transactions on the Steem blockchain are permanent and public.
What does it mean?
When you publish a post, it remains forever in the blockchain and you cannot delete or edit it. And the same is true for votes, comments, Steem transfers, profile updates and pretty much for every transaction that is broadcasted on the blockchain.
Wait, I can edit things!
When you edit your post, the old one doesn't disappear from Steem.
Platforms like Steemit or Busy shows your latest edit only, but with access to Steem, e.g. with a blockchain explorer, anyone could read your entire Steem history.
Right to be forget
There are times when you change that much that you want to clear things from your past.
As I've written above, you cannot delete your profile. All you can do is abandoning your profile. So be cautious with what you share.
Using a nickname is a clear winner against your real name in this manner.
Also, using niche blogs provide less information about your whole identity, so multiblogs are better then a simple personal blog when we consider privacy.