WhatsApp announce a new function called ‘Delete for Everyone’ which allows the user to delete a message they sent within 7 minutes of it being sent out. this may help someone who sends a message and then regrets their decision. This option will be for individual messages or those sent to a group chat. Exactly when this new function will be available on our phones is unclear.
You can see full details of this function in this article.
And WhatsApp own delete FAQ here