Steps to delete a single text message on your iPhone 8

1. From the home screen, tap Messages.
2. Tap the message thread as needed.
3. Tap and hold the preferred message.
4. Tap More....
5. Select the desired messages.
6. Tap the Trash icon on the bottom left corner of the screen.
7. Tap Delete Message to confirm.
8. The message has been deleted.

Note: To delete all messages, tap DELETE ALL, then Delete Conversation.