Hello and welcome to Apple Support Communities, Kia175.
If I understand your post correctly, you no longer need a shared calendar event that is reoccurring. I’d like to help.
If the event was created by someone else use these steps:
If you want to stop subscribing to someone else’s calendar, you can unsubscribe from it.
In the Calendar app
on your Mac, Control-click the calendar in the calendar list, then choose Unsubscribe.
If you don’t see the calendar list on the left, choose View > Show Calendar List.
See the full article here:
Subscribe to calendars on Mac
If you created the event you can delete with these steps:
Add, modify, or delete events in Calendar on Mac
Let us know if that resolves this issue for you.
Thanks for using the Apple Support Communities. Take care.