Go to the quiz results page. If necessary change the settting to 'All attempts' from 'Attempts by enrolled usres'.
Then you can delete the attempts.
Then you can delete the attempts.
Great. Thanks Tim. "all attempts" did make them show up. I then had to look at some youtube video to find out how to delete them. All fixed!
thanks again
Kris
PS: I personally find that the location of the boxes to "regrade selected attempts" or "remove selected attempts" should be moved/copied to the top of the list, as opposed to the bottom, but that seems to be a general Moodle design choice.
Interesting. Those links have been at the bottom of the table for years, but perhaps in that time a different convention has arisen.