It has been 4 years since I had my 99 Trooper, but IIRC the bumper assembly comes off with 4 bolts at the frame rails, and possibly some sort of connectors around the sides to keep it from vibrating. You will need to disconnect the fog light connectors also if you have them. There is a thin sheet metal "bumper" under the plastic...whether you impacted the metal is hard to say, probably not.
95 Trooper LS - 4" lift, 35" tires, 5.38 gears, ARB lockers
"Speed has never killed anyone. Suddenly becoming stationary, that's what gets you." - Jeremy Clarkson