How do I unsubscribe from a calendar (i.e. delete a calendar subscription)?

Open the macOS Calendar application.

Double-click on any event in the calendar you wish to remove. In this example, such an event is the Labor Day.

A window opens showing the details of the selected event. At the bottom of this dialog, click the Unsubscribe button.

If there is no Unsubcribe button, there are two possible reasons:

• You are using an old version of the macOS Calendar application. Please see calendar removal in older versions of macOS Calendar.
• You have selected an event from calendar which can't be unsubscribed (not one from WebCal.Guru). Please see Apple's article Add or delete calendars on Mac.

A dialog opens to confirm that you really want to unsubscribe. Click the Unsubscribe button.

Please note that this will not only remove this particular event (Labor Day in tbis example). Instead, it will remove all events in that calendar. In this example, that calendar is US Federal Holidays.