If Applied Correctly, the Grout Should be Flush
When applying grout to a tile floor, use a rubber float to smooth the grout over the tiles and push the grout into the grout lines. Always use the float at a 45-degree angle moved diagonally across the tile to avoid digging out the grout lines.
When you are finished, the grout line should be flush with the height of the tile.
You Should Be Worried About Grout Width Instead
The width of your grout line determines the type of grout you use. There are two types of grout, sanded and unsanded.
If the grout line is 1/8 inch or less, use unsanded grout. If the grout line is any larger, sanded grout is the more stable choice, since the addition of sand helps prevent shrinkage as the grout dries.
If you carve out the grout below the line of the tile, you can weaken the bond between the tiles, leading to loose or broken tiles. A grout line above the tile creates a sloppy look and could lead to tripping.
Using the right grout and proper technique will give you perfect grout lines every time.