If it's cured, scrape it off, or use a single edge razor blade. If it's thick enough you may be able to pull one end, or try rolling it off. I don't know of a chemical that dissolves it.At LHS I was told to use to use clear silicone for the bathroom corner walls. I don't like the look and want to buy the colored mapei stuff for the corner walls. What do I use to remove it?