The ability to erase a message does not erase the moment somebody organized their feelings around it.

Deleting a message removes it from the screen. It does not remove the fact that someone read it, felt something, and adjusted their evening or their sense of where they stood with you. The retraction is available to you and the experience already happened to them.

Before sending something in a strong emotion, remember that the send is the irreversible part. And if you have deleted something someone saw, address it rather than pretending it did not exist. A brief acknowledgement of what you sent and why does far more than a silent removal.