Open your calendar tab.

At the left I have a narrow pane which lists the calendars, and shows the colour they use. If you don't have this, go to

View|Calendar|Calendar Pane and tick "Show Calendar Pane"

Now, in that left-hand pane, right-click any of the calendars, select "unsubscribe". Done.

Add a calendar? File|New|Calendar Import a calendar? Events & Tasks|Import…

Please explore and learn your menus. They are there to help you.

There is no "unsubscribe" on my calendar. Please read the menus? Perhaps you should have R E A D what I had said & be nice, maybe just maybe I don't see as well at my age as I did when I was younger !

see3ducks said

There is no "unsubscribe" on my calendar. Please read the menus? Perhaps you should have R E A D what I had said & be nice, maybe just maybe I don't see as well at my age as I did when I was younger !

Someone is trying to help you and your response is less than polite.

If you have trouble seeing, I suggest you retain the services of an optometrist or an ophthalmologist instead of complaining about it here. We can do nothing about your vision.

see3ducks said

I am want to totally clear the lightning calendar - how?

You could remove the Lightning add-on, but I really do not think that is what you want to do. Personally I delete or unsubscribe from the individual calendars. Based on your reply to Zenos, I am assuming you think the calendar grid is a calendar. It is not. It displays information from all of your calendars. Using colour to delineate the source calendar.

I want to unsync the calendars

unsync it from what? I have no idea what calendars you have added, but I get the feeling you have more than one.

On the off chance it is a google calendar.See https://support.mozilla.org/en-US/kb/using-lightning-google-calendar

I want to add a calendar

https://support.mozilla.org/en-US/kb/creating-new-calendars

I want to import a calendar

From what source and in what format. Like there are lots of kinds of cheese, there are lots of kinds of calendars and one size does not fit all. This might help https://support.mozilla.org/en-US/kb/adding-a-holiday-calendar

How to all of these please.

Note that if you do not have a menu bar across the top of Thunderbird. Right click the toolbar at the top and select that the menu bar be shown. F10 will make it visible for a short time.

You sure see something different than I do. I only show 9 items and one of those is grayed out. I have the latest version offered. Perhaps I imported a calendar years ago or something. Anyway, I'm still wanting to blow it off.

I tried deleting Lightning but it still keeps coming back. It must be stored somewhere.

Thanks

OK so 9 items and one is greyed out. What about the other 8?

How and where did you "delete" Lightning? The wording here is "remove".