How do you de activate anti theft system on your Ford Fiesta?

To deactivate the anti-theft system on a Ford Fiesta, you typically need to use the key fob to unlock the driver's side door. If the system has been triggered, inserting the key into the ignition and turning it to the "On" position without starting the engine can also reset it. In some models, pressing the unlock button on the key fob twice can help as well. If problems persist, consulting the owner's manual or a professional may be necessary.