title: Destroy previous page (NavigationService.GoBack()) in WPF Windows Phone 8
body: <p>I'm new to developing windows phone 8 application, In that first page is <code>UserRegistration.xaml</code>. After completion of user registration process it goes to <code>MessageList.xaml</code> page, It's fine but when press back button of windows phone it goes back to the <code>UserRegistration.xaml</code> that I don't want.I want to close the application after clicking on back button but the application keeps the previous page in stack for navigation( <code>NavigationService.GoBack();</code>). So how can I exit the application from <code>MessageList.xaml</code> page or how can I collapse the  previous page activity?</p>