iCloud calendar will not stay deleted

My iPhone is set up with a yahoo email. I created a new iCloud calendar in the iphone app and then changed my mine and went to delete it. It disappeared and then reappeared seconds later. It will not delete. My calendar is not synced with yahoo email/calendar; as it does not appear on their website calendar. I can received shared apple calendars as well but those also will not delete; even after the sender has deleted it on their end. I also cannot share my own made calendars with others. I can receive from them but not add them to mine. It looks like the invite goes out and then they disappear under the "shared with" tab.

I have restarted my phone and updated it to iOS 18.6.2