To be able to use any Calendars, you'll have to add users within the calendar first. This will also allow you to edit them and customize them to your liking.
To get started, Navigate to the Calendar settings under the Settings Category.
Deactivate Calendar
You can deactivate your calendar by selecting the 3-dot menu of the calendar. Click on the Deactivate Calendar option to deactivate it, and a confirmation message pops up, click on the Save button to confirm.
Activate Calendar
To activate the calendar click on the activate option and a confirmation message pops up, click on the Save button to confirm.