What do you mean exactly by disable the apps? If you mean how to close them, drag the app from the topmost edge of the screen to the bottom to close it. Alt+F4 also closes them using the keyboard.
If you mean how to completely remove Metro apps, then here is how you can uninstall the built-in apps:
http://winaero.com/blog/how-to-remove-a ... windows-8/. However, some apps like Photos, SkyDrive, Store, PC Settings cannot be removed. You can unpin them and change the defaults to desktop equivalents such as Windows Photo Viewer, Windows Media Player etc.
To change the defaults to desktop apps, open the Desktop Control Panel by running control.exe -> Default Programs -> Set your default programs.
To boot to the desktop instead of the Start screen, open Taskbar and Navigation Properties from Control Panel -> Navigation tab -> check the option to boot to the desktop.