As the above post said, you can use a small hacksaw (if you can find one for tight spaces, i.e. that doesn’t have the “bow” on top) to cut them down. I would add one thing though. You might want to put a cloth or piece of cardboard or something behind it when you use the hacksaw, just so you don’t scratch the porcelain. Speaking for myself, I can try and be careful but I almost always nick whats behind it. Go slow and make short little strokes, unless you can make full strokes without hitting the porcelain. Take your time and you should be able to cut through the bolts fairly easily. Just a suggestion!