I want to deregister my iphone4 serial number from my account so that I can sell it to someone else.
I tried to find "manage device" button on the account information page but couldn't find it.
I have similar same problem. After deleting my old iPhone from account the 'Manage Devices' dissapear from my account information in iTunes
You have to turn on automatic download
After that, 'manage devices' are back in iTunes account
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