In this case we need to cut a square in the tile for drainage. To do this, lay the edge of the tile you need to cut against the one that is laid next to the drainage hole. Mark on the tile along one edge the length of the drain. Then turn the tile on its side, hold it against the tile above and mark the width of the drain. Draw lines across the tile to mark the length and width of the drainage hole. Now in a well-ventilated area, use your angle grinder to cut out the square for the drain. Once you have cut the outline of the drain, cut a diagonal line across the square to make it easier to push the off-cut out. Lay the cut tile over the drainage hole.