Deleting archived messages from Messenger can be done through the Facebook website or the Messenger app on mobile devices. Archived messages are conversations that have been hidden from the main chat list but are still accessible through the archive. Deleting archived messages permanently removes them from the archive and cannot be recovered.
There are several reasons why you might want to delete archived messages. For example, you may want to remove old conversations that are no longer relevant or that contain sensitive information. Deleting archived messages can also help to free up storage space on your device.