Remove old email from my calendar on iPhone

Hello brianadams310,

We would like to see how we can help you with removing an invitee. Have you tried removing them from iCloud.com? If not, follow the steps in this link to delete an invitee: Invite people to a calendar event on iCloud.com - Apple Support

"Edit or delete invitees

1. In Calendar on iCloud.com, double-click the event to open it (if it isn’t open already).
2. In the event window, click the arrow to the right of the invitee’s name, then do any of the following:

• Change an email address: Choose Edit from the menu, then edit the email address.
• Delete an invitee: Choose Remove.

3.To close the event, click OK."

Cheers!