Deleting a message or conversation from your archived messages won't delete it from your friend's inbox; a record of the conversation will still exist unless they delete the archived message as well.
What happens when you delete archived messages?
Touch and hold each conversation that you want to archive or delete.
- Archive: To put the selected conversations into your archives, tap Archive. . ...
- Mark all as read: Tap More. Mark all as read.
- Delete: To delete the selected conversations from Messages, tap Delete .
Do archived messages stay forever?
The Archive action removes the message from view in the inbox and puts it in the All Mail area, in case you ever need it again. You can find archived messages by using Gmail's search function. ... The Delete action moves the selected message to the Trash area, where it stays for 30 days before it is permanently deleted.
