How to delete all the events created on Calendar?

As a Google workspace user you can delete all events in the calendar. If any event has guests, it will be removed from guests' calendars as well. For example, in the future if the user leave the organization the event notifications will be going to the members of the event.

Steps to delete all calendar events

Step 1: On your computer, open Google Calendar

Step 2: In the top right, click Settings

Step 3: In the left column, find the calendar you want to delete.

Step 4: Click the name of the calendar.

Step 5: Click Remove Calendar -> Delete 

Step 6: Delete Permanently

Note: All events in this calendar will be deleted. If any event has guests, it will be removed from guests' calendars as well.

Please find the below article for your reference:

https://support.google.com/calendar/answer/37188?hl=en