How to Turn Mac off at Set up Screen

Hi, I am getting rid of my macbook pro and completed all the instructions posted on mac support here http://support.apple.com/kb/ht5189, however the last instruction is:

After you reformat your hard drive and reinstall OS X, the computer restarts to a Welcome screen and asks you to choose a country or region. If you want to leave the Mac in an out-of-box state, don't continue with the setup of your system. Instead, press Command-Q to shut down the Mac. When the new owner turns on the Mac, the Setup Assistant will guide them through the setup process.

I am at the set-up screen but command Q is not working - I didn't want to just hold the power button down. Can anyone tell me why command Q wouldn't be working and what my other options are?

Thank you!