what are you putting in the 30 dave?
That's what I meant. Don't smash it you can reuse it as the lidI agree with hypostatic. I think it would be much easier to try and cut/scrape the silicone away with a razor blade. I would be worried about damaging the other panels of glass.
It is very easy to remove the frame and panels of glass. I did this on a 115 gallon without any problems. I got the front panel cut so it fit for the top and a 12 inch piece in the front. Here is my thread if you want to see the process i did for a slider door.
http://www.dendroboard.com/forum/members-frogs-vivariums/61126-so-begins-125gallon-saga.html
Ed Parker
Here is a link to the Tutorial that I did where I used front glass of the tank to make a sliding glass front.Just use a razor blade as others have stated. Ive done this to turn my 75 gallon into a "turtle" tank with a filter hanging off the backside. Hardest part of that broject is getting e channel, which can only be found online from my experience.
Also- quick tip- silicone does not adhere to silicone. So make sure you have a nice strong bead or youll be scraping it all off and starting again (the parts that need to be water tight of course.)