Hey cyberlawprof,
If you follow the steps to delete a message in Messages from this article, are you able to remove that? Delete and recover messages on your iPhone or iPad - Apple Support
"Delete a single message
- Within a conversation, touch and hold the message bubble to open an options menu.
- Tap More
. - Tap the Trash button
, then tap Delete Message.
To keep your messages for a certain amount of time, go to Settings, tap Messages, then tap Keep Messages. Then select how long you want to keep your messages.
When you delete a message, the message only disappears from your Messages thread, not from your contacts' threads. To remove a message that you accidentally sent from everyone's threads, use undo send.
If you use Messages in iCloud and delete a message, photo, or conversation on one device, it’s removed from all of your devices."
If that doesn't help, we'd recommend contacting Apple Support for further assistance here: Apple Support
Thanks!