Use A Worm clamp (radiator hose clamp) large enough to fit around the exhaust with heat shield in place. tighten up and it will be fine. use two (one on each end if needed). You can find clamps large enough at any reputable parts house/store.
Note* you do not want to just "yank it off" especially if a fuel line is close to it. It was placed there for a specific reason by ford, to shield surrounding components from the extreme heat produced in the exhaust. good luck.
