They are siliconed in on the top rim, you have to saw through the trim just where it meets the back wall of the tank, i used a fine bladed hacksaw and went really slowly, after that you need to lift it up, it will take some lifting at first but when you start to break the silicon it gets really easy, the full trim will come off in one so you can put it back in situ if you dont like the look.
The nice thing is the glass is bevelled and finished off to a good standard and to be honest you would never knowvthe trim was there bybthe time you are finished.
Are you thinking about doing this mod, if so i can talk you through it in more detail