Top right-hand corner, you will see your user name and underneath that, in tiny letters "profile | sign out".
Click on "sign out", and in future when you log in, uncheck the box that says "keep me signed in".
" W8 is a great OS"
LOL. Windows 8 on a laptop or PC is just Windows 7 with a few bits removed, and a clunky interface stuck on top.
It's not an OS, it's a branding exercise in an attempt to push Windows users towards Microsoft tablets.