If you are disarming the system with the intent of testing the system, do not! The SRS is a sensitive, complex system and should only be tested or serviced by a qualified automotive technician. Also, specific tools are needed for SRS testing.
Disconnect the negative battery cable from the battery.
Disconnect the positive battery cable from the battery.
Wait 1 minute. This time is required for the back-up power supply in the air bag diagnostic monitor to completely drain. The system is now disarmed.