WhatsApp says the new feature will allow users to delete sent messages up to seven minutes after they have been sent, letting them delete hastily written on potentially embarrassing messages.
In order to be able to delete sent messages, both you and the recipient have to be using the latest version of WhatsApp.
How to unsend messages on WhatsApp
Open WhatsApp and go to the chat containing the message you wish to delete.
Tap and hold the message. Optionally, tap more messages to delete multiple messages at once.
Tap Delete at the top of the screen > Delete for everyone.