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Don't worry about it, I did the same thing when I had the iPad 2. Just call AT&T's customer care and they will be able to help you get that canceled.
 
i did the same thing. i called verizon, gave them my phone number, and they closed the account associated with the number.
 
As everyone has said, canceling AT&T accounts via the online method is the easiest way. I tried calling them and they didn't really couldn't do it unless I had the phone number associated with it. I've done this for my own AT&T new iPad and 2 other AT&T new iPads.

Question is, how do you access the VZW iPad account online? Aside from logging in through the iPad and calling VZW? Basically, similar to AT&T's method described above.
 
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