You shouldn't set anything into compatibility mode unless you have to and in most cases you dont' have to. Best to just pretend that setting isnt' even there.
Now, why do you want to deactivate that mode? Why is it enabled?
If it's enabled then you musty have set it that way. So, to deactivate it you do the exact same thing you did to enable it.
If you dont' remember, Right-Click on the shortcut for the program and then click on PROPERTIES. Click on the COMPATIBILITY tab and at the top you should see RUN THIS PROGRAM IN COMPATIBILITY MODE FOR... with a check box beside it. UNCHECK the check box and click APPLY. If it is unchecked then leave it alone, compatibility mode is already disabled.
There you go.