Removing grout by hand can be a tedious and time-consuming job, so you may want to find an easier way to do it. There are ways to use drills or grinders for grout removal, and also a specialised tool you can purchase for the job.
Power Grinder/Dremel Tool
You can use a power grinder or a Dremel to remove grout. The grinders come with a wide variety of bits and tips that will allow you to perform a wide variety of tasks. These bits are very strong and can cut through tile or metal, drill holes, and even cut the tracks for shower doors, besides efficiently removing grout from the sides of tiles.
You can also use a specialised drywall tool called the RotoZip for grout removal. This tool uses bits that cut from the side. RotoZip bits are made to cut into tile, so grout is not a problem. Both RotoZip and Porter Cable make bits like this for the RotoZip tool.
However, the RotoZip can be much more difficult to control than a Dremel. Take some time to familiarise yourself with the tool before you use it.
Grout Remover Tool
A specialised grout removal tool is probably the best and most efficient option. Unlike Dremels or RotoZips, The Grout Remover does not rotate. Instead, it vibrates. This helps to lessen the damage to the surrounding tiles.
The Grout Remover comes with a series of bits that are designed to remove different amounts of grout. Designers of The Grout Remover intended the tool to remove sanded or non-sanded grout from joints 1/8-inch wide or less. For more than that, try other tools such as the Fein Multitasker tool with a grout removal blade, or the Grout Grabber.
If you are only planning on doing one or two grout removal projects, the Grout Wand can fit on both a Dremel and a RotoZip and is far less expensive than purchasing an entire tool.