1 Boot into single-user mode
2 At the command-line prompt, type mount -uw /
3 rm -R /Library/Preferences
4 rm -R /Users/YOURUSERNAME/ <-- replace YOURUSERNAME
with whatever your user name is
5 cd /var/db/dslocal/nodes/Default/users/
6 ls (to list the files)
7 Delete the file that is named after your user account with a .plist
extension. For example, for user name "stevesande" you'd type
rm stevesande.plist
8 rm /private/var/db/.AppleSetupDone
9 reboot
At this point, OS X restarts and the Setup Assistant launches
automatically, initially asking you what language you want to set up
the Mac in. Since you're going through this entire dog-and-pony show
to set up the Mac for a new user, you don't want to run Setup
Assistant again, so just press Command-Q at the language screen,
then click the Shut Down button.
When the new owner boots up their shiny "new to them" Mac, they're
greeted with the Setup Assistant just as if they'd picked up the device from the Apple store
