Can’t delete calendar entry

I helped a friend get the Simple Calendar plugin installed on their wordpress site and create a google calendar, etc.
She had never used google calendar either, so when she added her event, it had the wrong date (it was either added as a repeating entry or she just had it lasting alot of days in a row…. We fixed the date. but it still has that extra entry on the 21st. The actual google calendar doesn’t: https://calendar.google.com/calendar/embed?src=etrorcalendar%40gmail.com&ctz=America%2FChicago

I have suggested that maybe if she completely deletes the event on the 20th, it will also delete the event on the 21st. but we’ll try to wait and get a reply from you all.

The page I need help with: [log in to see the link]