It is under about 40psi of pressure. There are various ways of draining it off. The one preferred on this forum seems to be to kill the pump with the inertial fuel cutoff and run the engine until it stalls. The shop way is to bleed the pressure off through a fuel pressure gauge which has a hose to safely let the fuel run into a container. If you release the pressure at the fuel rail's test port by hand, you have a chance of getting sprayed with fuel.
Anyway, however you release the fuel pressure, you will need a fuel line disconnect tool. There are two flavors, one is a scissors type metal tool that has two sizes. The other is a set of plastic collars. Both do the same thing, the plastic ones may be easier. There are posts somewhere on this site describing the procedure with pictures.
My main point is that knowing a code doesn't give you enough information to buy parts. All you know so far is that under some condition, your truck ran lean. Among the things that could cause this, in no particular order: vaccum leak, fuel pump, fuel filter, fuel pressure regulator, bad MAF, dirty MAF (on decel), bad O2 sensors. Many of these only cause problems in certain conditions, for instance a vacuum leak doesn't cause problems at high RPM or at high load. A fuel filter will cause problems at high speed and load before it will at idle, etc.
If your truck seems to run OK when under load (no surging or loss of power) it is probably NOT the fuel filter. A rich condition is not urgent, but a lean condition can be. Good luck.