Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I shut down all apps and tried to remove Office365, I couldn't.
I restarted the PC - still not able to remove it.
After a cold start I was able to uninstall and re-install Office 365 without getting the error.
That was on October 22.
Today is October 27 and the problem has returned.