We are replacing the vanity top in our bathroom. We are keeping the current vanity. The top is glued to the vanity. We managed to get the front and both sides unglued but cannot get the back part along the wall unglued. The backsplash is one piece with the countertop so when we lift up the front the backsplash hits the wall preventing us from lifting it further. Any suggestions on how to get the back part unglued?