Can you remove excess grout on slate tile after sealer has been applied?

I am currently working on this problem myself, having waited too long to clean tiles after grouting. We are using steel wool pads and spackle implements to scrape off the excess grout. I thought it might damage the tile but it really has not. It's a tough job, good luck. I am currently working on this problem myself, having waited too long to clean tiles after grouting. We are using steel wool pads and spackle implements to scrape off the excess grout. I thought it might damage the tile but it really has not. It's a tough job, good luck. Also a mild solution of sulfumic acid will remove most cement products... available at Home Depot .