How to restore an apple macbook pro to factory default?

If it came with Lion, 10.7.x or later, restart and hold down the Command+R keys. When you get the menu, run Disk Utility. Choose the hard drive and erase it. Quit Disk Utility. Then run the option to reinstall the OS.

Selling your Mac / Resetting the computer to the factory condition

http://support.apple.com/kb/HT5189

http://www.thesafemac.com/how-to-prepare-your-mac-for-sale/

restart and push de key C in you keyboar and show screen with initial hardware dvd and insert DVD INSTALL MAC OS and click in DVD for install.