How do I remove or reset the default text that appears on the Messages app?

I rely on Voiceover (because I’m blind) which sometimes results in very wierd key combinations. Somehow I have created a default ‘Message’ which is present everytime I start a new message. It doesn’t end up going when I send the text, but it’s a personal message I sent a couple weeks ago and don’t want it sitting on my computer everytime someone may come to help me.

How do I change it back to whatever it started with?

M1 Mac Mini

[Re-Titled by Moderator]