I don't know what Fast User Switching is. I didn't know I had a choice not to put my name there. It's just there. Do I command+drag to trash? I will await your reply.
Well, there was the root of your problem all along, calendar and battery notwithstanding. You can either command-drag your name from your menu bar - just off the bar 'til you see an "X" indicator, and then release...no need to trash it - or uncheck the box in System Prefs. (As I mentioned earlier, Apple and 3rd party apps often place icons that you don't need in your menu bar, so any time a new or curious one turns up it pays to investigate its nature.)
In the end, though, this was a good learning experience for you, so the long journey was well worth the effort.
If you didn't notice, and if it makes a difference to you, Jon's link points to a page that defaults to Big Sur instructions; you can change it to Catalina in the top left corner. (I've noticed any number of Apple pages doing that recenly, so it's always best to check before following instructions which may be totally inapplicable.)
And for future reference, if there's info in a screenshot (or other image) that you don't want to show, you can open the image in Preview and drag your cursor around it to surround it with blue dots, and then hit delete to white it out, like
so and
so.
