You can see your Trash from Google Calendar on your computer. In Trash, you can:
See deleted events for 30 days
Restore deleted events
Delete events forever
In https://calendar.google.com
Click the drop-down to the right of the calendar you want to work with.
Select ‘View Trash’.
To restore an event, click the checkbox to the left of the event and click the ‘Restore selected events’ button.
To delete an event(s) permanently, click the checkbox(es) to the left of the event(s) and click the ‘Delete forever’ button.