A deleted contact's birthday is still showing up on my birthday calendar.

Good to know, Bjmaxwell55.

Let's try a few simple fixes, try quitting the Calendar app. Then relauch it: Close an app on your iPhone or iPod touch - Apple Support

If not, are you able to delete the Birthday reminder in the Calendar app? You should be able to go to the event, then scroll down to "Delete Event".

Let us know if that helps to solve this, cheers.

Hi Bjmaxwell55,

We understand that your calendar shows events for a deleted contact. Does the contact remain in any email accounts you have saved on your device? If your calendar is synced with your email accounts, the contacts birthday can appear through it.

Set up mail, contacts, and calendar accounts on iPhone

Have a nice day.

Bjmaxwell55,

Thanks for the updated information. In that case, the next step will be to Contact Apple Support directly for further assistance.

Take care.