I see that you can close an App by grabbing the top of the screen and pulling downward but I do not see how I can do this through programming.  I want to add a close button (app has sensitive data I want it to shut down).   I see no methods in the Application to do this. 

Edit:

Maybe I just hide the data on the screen instead for security.   Windows 8 store apps big technical advances are you have a harder time finding an app to launch/start and then you have the same difficulty in stopping/closing it.  I don't understand why they did this.