Drilling?

[BCWolfen]

I emptied my old 33Gal FW today to plumb it into my SW setup and discovered (as I had forgotten) that it had been previously drilled in the bottom. This hole has been covered over with a square piece of glass siliconed all along the bottom and along the four edges.

I'm wondering what my best options would be here.

Should I try to remove the piece? Is there a good way to do it? Or am I risking crack
ing the base where the hole is?

Or should I get a diamond bit for my dremel and drill through the 2nd piece using the existing hole as a guide?

Any tips?