There are two methods for removing the wood trim on a Brodwax Fixture - depending on the age and model of the item.

Method 1 -  If the wood trim has screws on either one or both ends of the wood trim. Just remove the screw(s) to take the wood down. If there is only one screw, the other end will be held by an "L" shaped bracket, and that end will easily come off once the single screw is removed..

Method 2 - If the trim is hanging on rails from the electrical portion. If that is the case, you should be able to hold the wood by its sides and lift it toward the ceiling. Then slide the trim as far as it will go toward one side. The side now furthest away from the electrical portion should swing down past the fixture allowing you to remove it.