Hi,
Welcome to Microsoft Community! I'm glad to assist you with your issue.
To delete a calendar, please follow these steps:
- Sign in here
Select the calendar that you wish to delete in the list on the left.
Note: If you want to delete your default calendar, select "Options" from the toolbar and choose a different calendar under "Primary calendar" on the "Calendar options" page. Click "Save" to set the new default calendar.
- Left click on the calendar that you want to remove.
- Click Delete
Let us know if you need further assistance.

