You will agree with me that this feature is long overdue. WhatsApp users now have the ability to control their sent messages by way of recalling them or 'delete'. Before this update, you can only delete sent messages on your end, this would not reflect on the recipient's phone as the message might have been delivered.
With this newly rolled out feature, users can now remove messages they don't want their recipient to see, this occurs mainly in cases of error where you send a chat to the wrong person.
WhatsApp introduces "remove for all feature"
As found of the company's FAQs page
To delete messages for everyoneWonderful development from WhatsApp, feature comes in handy. Of course, you have to install your WhatsApp to get this feature.
Deleting messages for everyone allows you to delete specific messages you have sent to either a group or an individual chat. This is particularly useful if you sent a message to the wrong chat or if the message you sent contains a mistake.
Messages you successfully delete for everyone will be replaced with “This message was deleted” in your recipients’ chats (*). Similarly, if you see “This message was deleted” in a chat, it means that the sender deleted their message for everyone.
You can only delete messages for everyone for up to seven minutes after sending. Once seven minutes have passed, there is no way to delete messages for everyone.