As recently announced by Sony Playstation they have changed the conditions of service so that account holders could only have 2 active PS3′s for sharing an account on for games, same applies to the PSP. Previously it was possible to share your account across 5 systems but over many have used most of their accounts up having to replace old systems that have boken, making it impossible to deactivate via the machine.
Along with the new change in active accounts Sony have now made it possible at long last to deactivate you active systems via their Qriocity website. Unfortuately it is not possible to deactivate 1 system at a time, instead you have to deactivate all active systems then reactivate the systems you still use via the system accounts menu. This deactivation can only be done once every 6 months which seems perfectly reasonable unless you’re trying to some really strange sharing activities on your account??