The first thing you need to check is if the driver’s door is unlocked. Most car alarms turn off once the driver side door of the car is unlocked, so this should be the first thing that you should attempt to check in order to get the alarm to turn off.
In case that is not the issue that is causing your alarm to go off, then the next step is to put the key in the ignition and to then turn the car on. This is more than likely to turn off the cars alarm, since all alarms have a kill feature, which turns them off, once the car is turned on.
Another thing that you can do is to locate the car alarm fuse and to remove it. All car manuals come with locations as to just where the fuse box is located and just what fuse is responsible for what. However, if you installed the car alarm later on, you will have to play a guessing game.
Once you locate the fuses, all you have to do is pull it out. If you don’t know which one to pull, you can do a trial and error run, by pulling and putting fuses back in place, till the car alarm finally goes on and shuts off.
As long as you put the fuses back in place, there shouldn’t be any problems.
The last option that you have on your hands is to disconnect the car battery. Since the alarm can’t work without a power source, disconnecting the battery will turn off the alarm altogether. It will also reset the car alarm.