There's no simple way to cancel it even at this point. Even if you delete the message from the conversation thread — even if it is still in the process of being sent —your iOS device will still attempt to send it out in the background. Deleting a message only deletes your local copy of the message.
In this manner, are text messages ever really deleted?
Unfortunately, this isn't always the case. Text messages can remain on your phone until they are overwritten by other data. However, if you follow the steps above, all the messages will be deleted from your device – but are the deleted messages really gone? No.
How do you delete Imessages?
- Launch the Messages app on your iPhone or iPad.
- Tap on the chat you'd like to clear images.
- Tap the info button on the top right of your screen.
- Tap and hold on one of the images you'd like to delete under the Attachments section.
- Tap on More in the popup menu.
How do I permanently delete Imessages from my Mac?
Open Finder, and press CMD+Shift+G (or right click on Finder and choose Go to Folder…), type in ~/Library/Messages/, and click Go. Step 3. Here you will see the iMessage Chat Files. Delete the chat.db, chat.db.shm, chat.db.wal files from this folder, and empty your trash.