This is because your e-mail account is the main account on that Windows Phone, you will need to [reset your phone to change the Live ID](https://windowsphone.stackexchange.com/questions/205/how-can-i-change-my-live-id). On the Nokia Lumia you can alternatively [reset like this](https://windowsphone.stackexchange.com/questions/382/how-to-turn-off-windows-phone-if-it-is-unresponsive-and-has-an-internal-battery/384#384):

![][1]

**Note that you will lose all your data if you do this, [tag:backup] anything you still need...**


  [1]: http://i.stack.imgur.com/3F3wu.jpg