Boot into single user mode by, powering the system and holding down Command-s until you see the
system booting inside a black screen.
Mount the system with write access: ***make sure to put the "/" at the end of the command
/sbin/mount/ -uw /
Now delete the XML install setup file .AppleSetupDone this will be recreated at next boot and prompt for new user configurations.
Reboot the system:
shutdown -r now
Once you are back in the system you may not have access to your old User's folders. If this is the case you will need
to chown the old folders to your new user. Open up a terminal (can be found under utilities) and type:
sudo chown -R newUserName /Users/oldUserName