WhatsApp had introduced the 'Delete for everyone' feature quite some time back. Now, WhatsApp has introduced some new rules for the same feature in its Latest Update. Read more at bgr.in
With the 'Delete for everyone' feature users can delete a message in any given conversation. Earlier the time allowed to delete the messages was 7 minutes eventually it got increased to 1 hour 8 minutes and 16 seconds.
As per the Latest Update, WhatsApp states -
"if you sent a message to your friend and wish to delete the same, the message will not be deleted even after tapping 'Delete for everyone' unless and until your friend does not receive the delete request in the above mentioned time."