How to delete individual Facebook messages or entire conversations on your computer or mobile device

You can delete Facebook messages using the Facebook Messenger smartphone app, or the Facebook website.
Techno-Science.net

How to Delete Archived Messages in Facebook Messenger

Archived messages, a nifty feature of Facebook Messenger, is excellent for saving something you wish to revisit later or cherish for years to come. Safe to say, archived messages are the storehouse of ...