How do you disable 2008 Ford F-150 daytime running lights?

To disable the daytime running lights (DRL) on a 2008 Ford F-150, you can use the vehicle's headlight switch. Turn the ignition to the "On" position without starting the engine, then press the brake pedal and turn the headlight switch to the "Off" position. Hold the switch in that position for about 10 seconds, and then release it. This should deactivate the DRL feature. If this does not work, you may need to consult the owner's manual or a professional for further assistance.