Taking the bones out of a rainbow trout will likely be one of the easiest things you've ever done. If the fish is cooked properly, the bones will lift right out. In fact, a good way to know if you have fully cooked the fish is by attempting to pull out a bone. Be careful though, because tiny, transparent bones may still be in the meat even after you think you have pulled them all out.
Grab the fish by the tail.
Pull the tail away from the back and toward the head of the fish.
The head should come off along with the skeleton. Toss the bones in the garbage.
Open fish so that each side is flat.
With your fingers, pull out any remaining tiny bones you see.