Gargling with salt water might take care of those coughs.
I am not asking to switch admin role on and off; I maintain a non admin user in another browser for testing and I also use impersonate to see from a users role.
I have been merely looking for a way to use group messages to make announcements that regular users cannot reply to. And yes, in my latest test, I sent a group message and then closed it, and as a non admin user it is completely gone. So that means I would never even see it. What I hoped was a message sent that could be read and not replied to, but it seems not possible.