WhatsApp now allows you to delete messages that was sent by mistake

From WhatsApp support page;

To delete messages for everyone:

  1. Open WhatsApp and go to the chat containing the message you wish to delete.
  2. Tap and hold the message > choose Delete from the menu. Optionally, select more messages to delete multiple messages at once.
  3. Tap Delete > Delete for Everyone.

The feature is available WhatsApp latest version for Android, iPhone or Windows Phone.