I know Facebook doesn't allow users to delete chats from both side after 10 minutes. But is there any way or workaround to delete or vanish my sent messages from my friends' side?
One possible way is to report that chat as spam.
From Facebook Help Centre - report a conversation as spam:
- Open the conversation and click three vertical dots.
- Click Something's Wrong.
- Select Other > Spam.
- Click Send Feedback.