You can use power tools. There are a variety of tools, called grout removal tools or re-grout tools, which will help you remove grout quickly and with much less effort. These are helpful if you have a large amount of grout to remove or remove grout often. You can use manual tools as well. If you for some reason cannot use power tools but find that you have a reasonable amount of grout to remove, use a manual grout removal tool. This will look like a small trowel. If you only have a small amount of grout to remove or it is something soft like rubber grout, you can use a standard razor blade, like an exacto knife or a utility knife.
Cover the surfaces of the appliances you are planning to keep. As the grout is removed, flying debris can cause damage. Drape a large blanket or drop cloth over the appliances, making sure they are fully covered. If necessary, use tape to secure the edges of the protective covering and make sure to cover drains completely.
If you do not have a grout scraper, use a small, cold chisel and hammer or a knife blade. Angle the chisel away from the edge of the tile and tap if with the hammer until the grout is freed from the floor and edges of the tile.
If dried grout reside does harden onto the tile, you can try to remove it using vinegar, a chisel, or a diluted sulfamic acid solution.
