Just like everything else in this state it's all a money game. Like onetonbb74 said you have the option to non-op a vehicle but that still cost you 18.00 and is good until you decide to register the vehicle again.
Here is from DMV's website.
California law requires vehicles to be currently registered if they are driven, towed, stored, or parked on public roads or highways at any time during the registration period.
Non-operational means that the vehicle will not be driven, towed, stored, or parked on public roads or highways for the entire registration year.