How do you get the premixed grout off of the tile's after it has dried.

a critical aspect of tiling is to completely wipe away all the grout on the surface of tile so that the only remaining grout lies between the tile you have installed. If you fail to do this, especially if your tile is textured, it is next to impossible to remove the dried on grout. There are 2 acids available to work on this type of problem. The first is muriatic acid which absolutely should not be used because while it will remove the surface grout that you are trying to clean up, muriatic acid will etch and potentially remove the color from your work. The second acid is phosphoric acid which should work. Wear gloves and in a very small test area apply diluted phosphoric acid. Use a nylon brush to attempt to scrub off the excess grout. Increasing the strength of the phosphoric acid until it removes the surface grout in the test area. Once you find the right strength, work in small areas as you scrub and wipe away the surface dried grout. When you are done, clean the whole surface as you normally would. Take the necessary precautions to safely dispose of your cleaning materials.

There are several ways to remove the excess grout from tiles..This is one way that I have used for many years and works well for me..First of all I am assuming that you used a good Grout Float to sqeeze the grout between the tiles...I try not to let the grout set completely dry it becomes a real pain trying to get it all off..I have a small bucket of luke warm water and two or three Grout sponges..wiping the excess from the tiles and rinsing the sponges as you go..the excess grout builds up on the sponge very fast that is why I keep an extra one around..Basically wipe and rinse till you get the bulk of it off, also water becomes very dirty with used grout..dump it and use clean water often..Once you have got the bulk of the grout off.Rinse out sponges completely clean,a new bucket full of water, now wipe the remaining light grout of tile, let it dry you will have a haze over the tile wipe again with clean sponge and water let dry and should be good...Good Luck