It seems that clearing events from a 'secondary' calendar is currently not possible, even for users with elevated roles like Calendar Admin or similar.

While you can delete, create, and modify calendars or events, attempting to clear all events from a secondary calendar using the following endpoint:

https://www.googleapis.com/calendar/v3/calendars/_calendar_id_/clear

where _calendar_id_ is a value like an email, e.g., [email protected]) results in the following error:

{
  "error": {
    "errors": [
      {
        "domain": "global",
        "reason": "invalid",
        "message": "Invalid Value"
      }
    ],
    "code": 400,
    "message": "Invalid Value"
  }
}

If anyone has insights, a guide, or tips on how to clear events from a secondary calendar, your help would be greatly appreciated!