i need to disconnect ATT at Hand

I have been trying to disconnect my ATT at Hand service (think this is my phone) since July.  I have been on hold for more than 10 hours total (over two hours at one point.)  I have spoken to ATT personnel who have told me I have the wrong person and they transferred me to either someone else who also was the "wrong person" or to numbers no longer in service.

The website disconnect area in incomprehensible, it requires information you likely need to be an ATT engineer to understand let alone properly respond to.  There is a great deal on line about it being impossible to disconnect.  "No Exit" comes to mind.  HELP PLEASE!!