Unhook netlfix from xfinity account

I need to know how to unlink netfilx from my xfinity account. A family member is trying to add me to their netflix account. But everytime I try to respond to their invitation, it takes me to netflix on my xfinity account and asks which plan I want to select which includes the cost. I need to know how to get out of this. I have called your 800 number and visited the local store twice. So far no one has been able to resolve this issue.