Hidden calendars show up in the side panel

If I deactivate a calendar, its dates are still displayed in the side panel calendar view.
How do I get rid of those, short of deleting the calendar?
Im still on v9.

Really excellent support here. :confused:

To disable the calendar events / dates showing up in the Sidebar, “Hover your mouse to the right of the word Agenda” and then click on the “Cogwheel”. Then click “Choose Folders”.

Next “Deselect your Calendar” & click “Ok” as per the below Gmail Calendar example.