Calendar has thousands of duplicate yearly-repeating entries

Perhaps I need to completely restart my calendar from scratch. I have 3 yearly-repeating entries (each is for the birthday of a family member (for my child and my 2 step-children, but not for my wife) where each one is repeated over 5000 times. I think the highest number has been 5193 for my oldest child. I have other yearly repeating entries that have no problem. I have only my "Home" calendar checked, though I have in the past had my wife's shared calendar also checked. For a while, it appears that when I deleted some of those thousands of entries, they'd just come back (judging by the count of "X ,xxx more ..."). But just recently, it seems I was able to delete some and the counts didn't come back. In other words, if I were willing to separately delete the 8 or 9 thousand entries, I might be able to get rid of them. But that would take me months and as far as I know, the problem could come back at any time. Maybe completely cleaning out my calendar and starting from scratch is the only answer. But what is the proper way to do that? I have 4 Macs and 1 iPad and store everything I can in my 2Tb of iCloud. What are the best ways to clean out my calendar? Or, if there is a way, what is the best way to clean out all calendar entries for a particular day of the year?