It is held in by metal tabs. if you don't care about the radio that is in there (what I expected), you should be able to stick a stiff thin piece of metal like a screwdriver down each side of the radio to release the tab.
If you buy a new radio it might come with the little tool to release the radio. I would love for you to pay me $125 to do it, but that is outrageous in my mind.
one time I took the dashboard off of a car to get the radio out, so if you cant do it any other way, that might be an option, but I am 99% certain that you can get it out with a thin piece of metal.
I did a search for radio removal tools and the flat thin piece of steel/aluminum type should get it out no problem.
I hope that helps.