How do I remove a line from my plan

You want to know what's ridiculous, it's when your new customer you leave your old carrier to come to them on a postpaid account. Take note I said postpaid. You create your login and all that crap and get your phone delivered late so that you're out of service for a day because they can't ship it in time and then you log into the account for the first time and it goes to a name you've never heard or seen before. Turns out my number was logged to someone else's account and still is for the fact that matter. Why you may ask I don't know why it's linked like that. But what I do know is these incompetent sons of b****** can't get your phone to you on time then they link you to a prepaid account under some guy you don't even know and then you can't get no f****** help it's worth a damn or anybody on that customer care line that you can even understand. This is got to be the absolute most shitshow company I've ever seen in my life. I want to file a complaint better Business bureau I'm going to let this be known to every public forum possible with screenshots no less. Thanks T-Mobile for absolutely just f****** everything up for me even more. Oh I forgot to mention the fact when you call and that dumbass automated line picks up it can't find your f****** number that they issued you why because it's a deactivated number under this person's account.