Before proceeding: Users should realize that when they delete a message or discussion, it is permanently erased as well as can not be recouped.
Keep in mind: These steps just get rid of a message or discussion from your account, not the one to which the message was sent.
Facebook Deleted Messages
Deleting a single message
1. Log into your Facebook account.
2. Select messages on the left-hand side of the Facebook homepage.
3. Open up the conversation including the messages you would love to erase.
4. Select the Actions Food selection Gear, and afterwards pick Erase Messages ...
5. Select the proper check boxes beside the message( s) you would love to delete.
6. Select Remove.
Removing a whole discussion
1. Log right into your Facebook account.
2. Select messages on the left-hand side of the Facebook homepage.
3. Open the discussion you wish to remove.
4. Select the Actions Menu Gear, then choose Erase Discussion.