Deactivate his console, log out and delete your user (he may need to do this from his account) on his console, activate your own as primary and change your password.
2 Step Verification is an added security measure just introduced that you might consider using. For information, please see here > http://community.eu.playstation.com/t5/PSN-Support/2-Step-Verification-now-available/m-p/24486152
NB.Game and account sharing/selling is against TOS and can lead to a suspension/ban.
