I would bet if you take a bright flashlight beam and look between the lens and the fiberglass, you will see to to four tabs sticking out and catching on the base of the assembly. They are press in and I made a tool for removing the lenses on my Winnie.
If all else fails call David at Lichtsinn and ask him.
"I travel not to go anywhere, but to go. I travel for travel's sake. The great affair is to go". R. L. Stevenson
David Bishop
2002 Winnebago Adventurer 32V
2009 GMC Canyon
Roadmaster 5000
BrakeBuddy Classic II