Issue with email associated with old account

Hello, I recenlty got a new Xfinity account and I want to use my email as my primary email, but I am unable to becasue that email is assoiciated with an old xfinity account I shared with an ex-boyfriend.

 I would like to remove it from his account so that I can use it for my personal account. Can you please help me remove the above email from any other accounts it might be assoicated with?

Thank you!

Miranda