You can do it online-Minds are like Parachutes. They work best when open. -There's no limit to what brainwashed people can rationalize
This is correct but you can't deactivate video this way. For that do as The_Geeky_Panda said and contact CS. 1-800-345-SONY
You can deactivate ALL Playstation systems (for games) once every six months via this page. For music and video, you need to contact Sony directly if you don't have access to the system you wish to deactivate.