How do you delete multiple calendar entries at once?

I have a client who has an extraordinarily strange situation. There are two events (both yearly repeating birthdays) that have somehow duplicated themselves to the point that each has 1,400+ copies on their respective days on her gmail calendar.

I'm looking for a way to quickly remove the events and was hoping to be able to use macOS calendar to do so. While I know it is possible to command click to select multiple events, that still isn't exactly a solution for dealing with 1400 entries.

Does anyone know of a way to select all the entries in a single day and delete them?

This doesn't seem to be possible in Google Calendar or Outlook either, and if there is no solution for macOS Calendar, I'm open to temporarily using a different calendar client to get the job done.

Thanks for any help!