Good afternoon gdub04,
Welcome to the Apple Support Communities!
I understand you are having issues with the Calendar app on your Mac. It sounds like the event indicated above is stuck and needs to be deleted. I'm assuming this event is not showing on your iOS devices?
Try the following steps to delete this event:
Force Quit the Calendar application - How to force an app to quit on your Mac
- Open System Preferences from the menu and choose Siri > Siri Suggestions & Privacy
- Remove the checkmark from in front of "Show Siri Suggestions in App" and "Learn from this App"
- Click Done.
Restart your Mac in safe mode - How to use safe mode on your Mac
See if you are able to delete this event while in safe mode - Add, modify, or delete events in Calendar on Mac
If you are successful, restart your computer normally.
Update your computer to macOS 15.5.5 - How to update the software on your Mac
Restart your Mac to refresh it and reestablish an internet connection.
Try creating a new event on your Mac.
Please reply to this thread if the issue persists after trying the steps above, and I'll do my best to help you with this!
Take care.