How do I get rid of white color on my coral colored grout?

It depends, what caused it - is it thinset that wasn't properly cleaned out before the grout was applied? Is it an issue with water leaching back through? In most cases they make a staining kit for grout which should help with thinset or other issues - follow the directions especially in regards to cleaning. If it comes back you have bigger issues

If the white is dusty and rubs off its possible efflorescence. The salts in the grout are migrating to the surface from moisture forming a coating. If this is so.....Mix baking soda and white vinegar in a cup to a paste like consistency. Use a small brush to apply the mixture to the grout lines. Allow the mixture to remain on the grout lines for a little while. Use a small scrub brush or an old toothbrush to scrub the grout lines. Wipe a damp cloth to remove the baking soda and vinegar solution. Let it dry then apply grout sealer to the grout lines.

Thank you. What about a drill with a stiff brush???

We can clean your grout with the most powerful product, which also preps and sanitizes the surface while releasing all the stains, mold and existing sealers. Then we will color seal the grout with Caponi , which is a titanium sealer and comes in more than 40 colors with a 5 year labor warranty. To learn more, visit : https://www.dsapone.com/georgia/atlanta/cleaning-grout/