How do you reset anti theft system in Ford F-150?

To reset the anti-theft system in a Ford F-150, first ensure that the vehicle is in the "Off" position. Insert the key into the ignition and turn it to the "On" position without starting the engine. Wait for about 10 minutes until the security light stops flashing, then turn the key back to "Off." Finally, turn the key back to "On" and start the engine; this should reset the anti-theft system. If issues persist, consult the vehicle's manual or a professional technician.