I have tried:
*Changing the previous events to be non-repetitive (including future events) also, I have done this and then the following in sequence.
*Manually deleting a current event and selecting delete this and all future events
Then, they pop up like weeds again, and every instance after one that is supposed to never repeat again continues to repeat.
It seems like this is an area where calender applications are kind of buggy. Thunderbird also did this.
It's getting to be kind of ridiculous.