Turn the ignition on so the dash lights come on, then press the gas pedal and brake pedal at the same time and hold till the spanner light flashes then it'll go out, this may take a couple of minutes so be patient. hope this helps.
If you have a technical or any other problem with a Ford Transit, try the Ford Transit Forum at www.fordtransit.org . It's free to sign up, and also has free private for sale ads and gallery. Hope this helps.