Delete spam calendars and events from your iPhone
If you receive unwanted calendar invitations or event notifications, you may have unintentionally subscribed to a spam calendar. To remove the events, erase the calendar subscription.
How to Remove Calendar Spam from Your iPhone on iOS 14.6 or Later
Tap the unwanted Calendar event.
Tap Unsubscribe from this Calendar at the bottom of the screen.
Unsubscribe to confirm.
How to Remove Calendar Spam from Your iPhone on Previous iOS Versions
Look for a calendar that you don’t recognise. Tap the More Info icon next to that calendar, then scroll down and tap Delete Calendar.
If this does not resolve the issue, delete the calendar subscription in Settings:
Open the Settings app.
Tap Subscribed Calendars.
Look for a calendar that you don’t recognize. Tap it, then tap Delete Account.