How do I exit a Modern UI app?

Solution 1:

• Use the keyboard. Alt + F4 still works like a charm
• Use the top edge:
  1. Move your mouse or finger to the top of the screen {except for the top left extreme and top right extreme}
  2. Click/tap and drag to bottom of screen. The app will close when you get to the bottom.
• Use the left edge: Bring the cursor in the very top (or bottom) left corner of the screen then move the mouse against the border up (or down). Now you can:
  • Middle click any app to close it.
  • Right click any app to show the contextual menu, with Close being an option.
  • Drag any app left onto the current app, then without releasing bring it to the bottom to close it

Please note that in Windows 8, in some cases apps are not supposed to be closed. This is part of the general Modern UI experience; however, because of popular demand, Microsoft did add this feature in the consumer preview.

See Microsoft's official video on mouse usage in Windows 8 here. Also a good video to watch is the touch video.

Solution 2:

Press the Windows Key, it's like a 'home' button.

It looks like it's you're not supposed to 'close' apps in a traditional sense, and should be in a 'suspended' mode instead this is achieved by just going and doing something else like going back to the home screen...

Solution 3:

Here is an answer from someone at MS on this forum thread:

The idea is Modern UI Style apps are not closed. The system takes care of keeping the apps from consuming background resources automatically. You can examine the app lifetime information in the developer documentation if you'd like. [...] Alt+F4 only works in the dev tools integrated builds as a developer feature and is not a general mechanism.