An earlier article described how emails can be unsent or edited using UnsendIt.
Now, apart from the web version, an iOS app is also available for free to download and use from the App Store.
Through this app, text messages sent from the iOS devices can be edited even after they have been read.
Also, this works even if the recipients don’t have the app installed. Only the sender needs to have this app installed.
The messages are fully encrypted and can be set to self-destruct any time as needed.
Do give it a try.