Hello
I have recently joined the club of unable to disarm the factory alarm without having a working remote control. The battery was removed for welding work, and the alarm came back when it was reconnected.
I have not found this information anywhere, including on the owner's book.
To disarm the alarm, hold the override button (I have attached the page from the owner book) and turn on the ignition (where the battery, brake, etc lights come on). Simple as that

You know this will work because the siren will stop immediately. If it did not work, switch on the accessories (battery light), hold the volumetric button and switch on the ignition.
Turn on the ignition as the manual indicates does temporarily stop the siren, however as soon as you turn it off the alarm would had gone off again!