How do you remove the light covers?

[CampingDixieDogs]

This may be a stupid question but how do you remove the light covers? There is styrofoam pieces in each one and I was going to clean it out but can't get the covers off....here is a picture of what it looks like:

[Gee Whiz]

This light fixture looks like the one's in my camper. You squeeze in on each side of the cover to remove.