what is the proper way to release the pressure and change the fuel filter inside the frame on e.f.i. system

 

Ford says to pry up the button of the inertia switch, then crank the engine several times to bleed the pressure out thru the injectors. If you don't want to pull your R kick panel out, though, you could just open the schrader (tire) valve on the fuel rail, but there'll be a little gas on top of the engine. It should evaporate safely by the time you get the filter changed, so it's not really a big deal.