Changing the color of your grout is a big job. I'd give it some time to get used to the color of your grout. Considering how new this ceramic tile floor project is, perhaps you are just suffering from the home improvement version of buyer's remorse. This happened to me recently when I chose a sand textured paint color based on a swatch. I swore it was gold but when it went up, it looked green! After the shock wore off, I decided I liked the paint color and have subsequently matched new furniture and accessories for the room based on the paint color.If you do want to change the grout, you have two options: removal or dyeing. If you want to remove the grout, I'd recommend a handy tool called The Grout Grabber (see photo). The Grout Grabber attaches to most reciprocating saws and allows you to grind out the old grout. Dyeing the grout is the other option. I'd suggest an epoxy based dye for maximum adhesion to the old grout.But again, I'd give it some time to get used to the color of your grout. You might end up liking the grout, and save yourself a boatload of work!