If you log in to Adobe.com with your Adobe ID and go to the registration area, you can get on a live chat with a tech who will help you through the process.
Chat wasn't particularly helpful, but during the 2nd iteration with Chat, I figured it out on my own.
FYI and future use: To deactivate, you must be in a project-work view (any project, new or old, it appears). Then and only then will "deactivate" be "hot" under the "HELP" pull-down menu.
My problem was I was trying to do it from the "gray" blank screen, with no project open, just the pull-down menus across the top. One would think that "deactivate" would work from such a state, but apparently not.
So it is what it is.
Solution as posted in my response.
Thank you for posting the details. That is good info, and will likely help others.
Appreciated, and good luck,
Great work, GI. Ciao!