To reset the factory OEM alarm, you would insert the key in the drivers door, turn left, then right to disarm and reset it.
If yours is malfunctioning, you can disable it for good by doing the following:
The FACTORY ALARM DISARM WIRE IS yellow/blue and located in the drivers kick panel in a white plug. Trigger the power unlock and the factory alarm disarm wires at the same time to disarm the alarm. Once Located, splice into either wire with a similar guage wire, and put it to a solid chassis ground. This terminates the alarm functions entirely.