Facebook Messenger will soon have ‘Unsend message’ button
Facebook is testing the 'Unsend Message' feature for Messenger. This will allow users to delete entire messages from a conversation while using Facebook Messenger.

Facebook is testing an ‘Unsend’ feature for Facebook Messenger. TechCrunch reported on the same after receiving a tip from Jane Manchun Wong, who accessed a prototype of the ‘Unsend’ button. A Facebook spokesperson then confirmed to TechCrunch that the feature could be rolled out in the months to come.
Wong also posted images of the new feature through Twitter. Currently, Messenger users are only able to delete messages from their inbox, though the sender/recipient will be able to see the message in his/her inbox. The screenshots shared by Wong show that the Unsend button will appear when a user selects a message and shows up above the Delete Message option.
If a user selects the Unsend button option, he/she will be able to delete the message from the chat on behalf of all its users. One should note, though, that the feature will only allow users to exercise the option within a limited time period.
Earlier in the year, the social media platform had detected a bug, that opened up Messenger chats for blocked contacts. Recently, the social media platform has admitted that 20 million people have been affected by a security flaw spotted in Facebook’s ‘View As’ options menu.