I have two accounts, one is disabled and the other isn't, whenever I try to log in the xfinity mobile app, it automatically signs me into the the disabled account. I tried to to change primary accounts but for some reason, it won't let me. If there's a way to remove a linked account, I would be glad to hear it.
We have now enabled the ability for you to eithe toggle and make an account primary or unlink accounts you do not want linked directly from the My Account website experience.
Go here for the new experience:
If you need a guide on how to do so, here's the Help and Support article:
Hope this helps, feel free to reply if you need further assistance.