Outlook 2011 won't close in Macbook Air
There are multiple ways to Force Quit a application.

The following is probably easiest.

Bring Up the “Force Quit Applications” Window

Hit cmd+Option+Esc to bring up the “Force Quit Applications” window, then click to select the app name, followed by clicking the “Force Quit” button to end the app immediately. 



Or, you could use the Activity Monitor to Force Quit application.

PS, it is also a quick way to see what apps are running :)