i don't have an fe in front of me, but if it does have a lever on the rewind knob, it is usually on the front side of the camera right at the base of the rewind knob -- you push the lever forward (it is spring loaded) with one finger and pull out on the knob with the others.

perhaps the knob is stuck in the film can somehow? Pull a bit harder -- nothing to lose. but don't use a pliers or anything.