Removing a line is way too difficult. I have been paying for lines that have not been active for years?

Removing a line from AT&T works the same way as it does for any other service provider - you must call.

611 from your AT&T mobile phone. 

You can use the key words 'cancel service' when you reach the robot phone tree and you will be transferred to the loyalty department where you can tell them which phone number you would like canceled off of your regular monthly bill.

Make sure you provide them with the correct phone numbers that you want canceled.

You must be able to prove you have the authority to cancel by knowing your security passcode.

If you don't know it, reset it online.

https://www.att.com/support/article/wireless/KM1051385/

As someone who used to work in the department (it used to be called Retention; it's called Loyalty now) that cancels service, I can assure you it's quite easy. 

1. Dial 611 from your AT&T phone or 800 331-0500 from any US phone. 

2. At the prompt say "Cancel service" or "Disconnect service"

3. When the rep answer, ask for cancel the line. They will verify your passcode and likely ask why and perhaps make various offers to change your mind. If none of those offers make a difference, be firm but polite in insisting the line be canceled. They will ask when and maybe give some explanatory information (such as the fact that the cancel is effective the last day of the billing cycle and the you will be charged as such). They might try to sell you  some other AT&T products. Again, if nothing appeals to you, simply firmly, but politely decline.

4. Exchange the typical parting pleasantries ("Thanks for being an AT&T customer, have a nice day" "Thanks for your help, you, too") and end the call.  

Easy peasy. 

I will add that you should check your account at the beginning of the next bill cycle to make sure that these lines have been removed from your account. If they have not, call AT&T, use the same words cancel service , and ask why these lines were not cancelled last month as requested.  

 If you have installments or contracts attached to them you will have a large bill for the remaining installments or ETF. 

At some point you file a Better Business Bureau complaint, and you should keep track of all phone calls so that you can refer to the date and time that you called  to make your cancellation request.

I think this is an ongoing intentional thing; it took me almost 3 years and 52+ hours of my time to finally get them to cancel a watch line was never opened!! I upgraded my watch and traded in the old one and they created a new line for the new one and left the old one as another line. They are telling me they can’t/won’t credit what I was overcharged; I think they are raking in a ton of money with this scam!!!