If you have unwanted events or calendars in Calendar on your iPhone, you can delete, unsubscribe, or hide them.
In the Calendar app, tap the unwanted event.
Tap Delete Event, then tap Delete Event again. Or if you want to report an event from an unknown contact, tap Report Junk, then tap Delete and Report Junk.
In the Calendar app, tap .
Tap the info button next to the calendar.
Tap Delete Calendar or Unsubscribe. If a calendar can't be removed (for example, the US Holidays calendar), you can hide it instead.
To confirm, tap Delete Calendar or Unsubscribe again.
In the Calendar app, tap .
Tap to deselect the checkmark next to the calendar.