Windows RT (Metro) apps can be uninstalled. Right-click and choose "Uninstall" from the menu that pops up at the bottom. Sometimes however, the Windows Store app notifies you that there's an update for an app that's been uninstalled. The reason for this is that the Windows Store app isn't notified when an app is uninstalled.
Fixing this requires resetting the Windows Store app's cache. Do this as follows:
- Press [Windows] + R on the keyboard to open the Run window.
- Type "Wsreset.exe", and press Enter.
If that didn't work, perform a clean boot (press [Alt] + F4 from the desktop, and select Shut Down from the menu, and then start your PC up again).