How do you disable a factory car alarm on a 2001 Ford Mustang?

To disable the factory car alarm on a 2001 Ford Mustang, you can try using the key fob to unlock the doors, as this often deactivates the alarm. If that doesn't work, you can insert the key into the ignition and turn it to the "On" position without starting the engine, then press the brake pedal to reset the alarm. In some cases, disconnecting the car battery for a few minutes can also reset the alarm system. If issues persist, consulting the owner's manual or a professional may be necessary.