Security Issue-Need my ex removed as manager

I am the Primary account holder and need assistance removing a former Manager from my Xfinity account.

When I try to remove this former Manager, Xfinity says:

“M****** A******* has an upcoming payment scheduled. Before changing or removing their role on the account, you’ll need to remove the scheduled payment.”

The upcoming payment is my own automatic payment using MY own payment method. I am the only payer on this account. This person has never paid this Xfinity account and has never lived at the service address. I don’t even know how he was made a manager.

I need Xfinity to correct the account/billing association that is preventing me from removing this former Manager for security reasons. 

I would like to handle this privately with Xfinity Support. Please let me know when I can send a Direct Message.