On the “Messages” screen, click on the conversation which contains the message that you want to delete. Find the message in the conversation, tap and hold, then drag left or right. The selected message will turn red. Then click on the red dustbin which has appeared in the top right of your screen.
You can also delete a selection of messages. Use the same method, but select multiple messages by tapping and holding them.
How do I delete an entire conversation?
On the “Messages” screen, simply swipe a conversation from right to left to expose the “Delete” button. If you’re sure, tap “Delete”.
On the Android version simply tap and hold the conversation until the prompt to delete the conversation appears
Warning! Once you’ve deleted a message or conversation it cannot be undeleted.
How to delete a message (above)
How to delete a conversation (above)