Unable to delete Outlook Recurring Calendar Reminders

I've been dealing with this on and off for more than a year. I go into calendar, search on Birthdays and delete them. In a few days or weeks, they are all back. I have searched repeatedly for an answer.

Here's what I have tried:

I've searched in the calendar for instances of "birthday" and used "shift del" problem returns

I've used the MFCMAPI tool, searched for instances of "birthday" and deleted. The problem returns.

I've individually edited the recurring birthdays individually to change to no reoccur.  The problem returns.

Today, I did an Uninstall of Office 365 (and the default mail app) using add or remove programs and then manually deleted the related folders in c:/users/myname/appdata/... and the problem returned.

So I repeated the previous exercise and then used the MS Uninstall Support Tool to remove and reinstall. I immediately get a notice of a Birthday that was on my calendar for today (but there is nothing actually showing on my calendar! ).

Help!