Nothing because you can't actually delete content from the blockchain. Under HF20, I believe you can now edit posts older than 7 days which you couldn't before, but you can't delete anything.
Even if you edit and delete what is there, a record of the edit AND the pre edited content will still exist on the blockchain. The reward which would have paid out after 7 days will stay paid out, and if less than seven days, will still stay with the post.
The lesson is:-
Be careful what you post, it is stuck here for ever!!
Your question is a bit flawed, because it's not possible to delete content from the Steem blockchain, no matter what you do. And the rewards will be with the person who gained them, unless they transfer it to another user. So don't worry if you want to edit your old post to "remove" them; they can't really be removed, they can only be hidden from certain blockchain UIs, and the rewards will stay exactly where they are.