Unsubscribe Calendar from iCal

These are the unsubscribe instructions from Apple:

How to remove a calendar on your iPhone in earlier versions of iOS

1. Open the Calendar app.
2. At the bottom of the screen, tap Calendars.
3. Look for a calendar that you don’t recognize. Tap the More Info button  next to that calendar, then scroll down and tap Delete Calendar.

📅 Unsubscribe from a Subscribed Calendar on iPad

1. Open the Settings app on your iPad.
2. Scroll down and tap Apps.
3. Tap Calendar.
4. Tap Calendar Accounts.
5. Look for the account labeled something like Subscribed Calendars (or it may list the calendar by name or URL).
6. Tap on the subscribed calendar you want to remove.
7. Tap Delete Account (at the bottom of the screen).
8. Confirm by tapping Delete Account again when prompted.

This will remove the calendar and stop it from syncing to your iPad.