I do agree, if you were to sell a Hive account, it would be nice to have an official function to sell the account, and maybe even a feature to delete postings from the account. Granted, all of the original posts would still be on the blockchain, but it would be like a fresh account on the interfaces.
It also raises the question, what happens when you sell an account that has a bad reputation score? I think that would play into a marker as a new owner as well.
I think a formal mechanism for selling accounts would be better than a backdoor mechanism. For example, scammers might want to buy accounts with a strong reputation to help push the scam. If the account were sold through a formal mechanism, the system could reset the reputation while those sold on the open market would not reset the reputation.
BTW: Selling accounts involves the IP rights related with an account. In some cases the seller might want to sell IP for images and texts in the account. In other cases, they might want to retain the copyrights. Such things could be stipulated in a formal contract and recorded on the blockchain.