Most of the time you won’t need to remove the trim ring once it is installed, but there are a few instances when you might want to know how. Perhaps you want to clean inside the diffuser, or change out your diffuser for a different style, or you want to protect the trim ring when re-painting the ceiling, or maybe you need to change out the light bulb on your light kit.
The trim ring clips into place on the ceiling assembly, so you will need to rotate the trim ring counter-clockwise until the clips line up, and then you will be able to gently pull the trim ring down.
When putting the trim ring back in place, make sure the gasket around the diffuser is not sticking out in places (if it is, just push it back into place), then line up the clips, and twist the trim ring clockwise until it is snug.
Here is a short video that demonstrates removing the trim ring and gasket: