Here is how I am removing the rim on my tank. Remove the center brace If you have one, I next used a hack saw carefully and cut the corners on the top and inside. The outside corners are a little trickier. You will need a small cutoff wheel like a Dremel and cut the corners carefully. Next I used a tool that is used for painting (pic below) to get in between the glass and tank inside and out to break the seal. (Safer than a razor blade). The hardest part is next. Take your cutoff tool and cut the top of the trim the length of the tank and the ends. The pic below shows how much room you have between the tank and the trim,(lots of silicone). After you are done gently lift the trim pieces off.(do not put a screw driver or anything else in between the trim and glass to pry or you might crack or chip the glass. Clean the glass with a razor blade and you are ready to go rimless. Unless of course you need bracing.