Top best answers to the question «Will blocking someone on facebook delete messages»
Nope. Blocking someone will not delete the conversation thread from any side. In other words, the old conversations will remain in Messenger, and you will be able to read them until you manually delete the chat thread.
If you choose to block one of your Facebook friends, messages you sent to the blocked friend will still appear in your Messages folder. You can, however, manually delete messages you previously sent to this blocked Facebook friend.