Yes, as you probably know, this is the factory anti theft system preventing the engine from running.
On the back side of the door lock cylinders is a small switch that turns off the alarm when you rotate your key in the door lock. More often than not, these switches either just fail, or they simply fall off the back of the lock cylinder......since they are just a push fit on the end of the cylinder.
There will be a switch on each door as well as the trunk......try all of them to see if you can get the alarm turned off.
If that doesn't work, then you'll need to remove a door panel so you can get to one of these switches and jump the 2 wires together to turn it off.