[AC Question]

My internet research reveals the following:

To delete a single message from a conversation

Open the conversation or group chat. (Done.)
Scroll to the top of the conversation and tap Edit. (This option does not exist.)
Tap on the message(s) you want to delete (a check mark will appear).
Tap the trash can icon at the bottom of the screen.

[mebobio]

Long press the message you want to delete, then once selected hit the trash icon.