A primary user has full access to an account’s features and controls the permissions for secondary users.
On the My Account page of Comcast.com, Transfer primary user allows you to make a secondary account your new primary account. Your old primary account will become a secondary account and will lose:
the ability to create and manage secondary accounts
the ability to manage some product features
the ability to view and pay bills unless granted permission by the new primary user
access to online voicemail (if you have XFINITY Voice) until the new primary user reinstates your access