Most of them have a very small slot, usually on the bottom that you can get a screwdriver or knife in to pry off the lens. If not you can usually press up, or squeeze both ends to get to pop off. All the ones I've had are just held on by plastic snap tabs. Good luck!
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder