Removing tiles from a floor can be noisy and messy, not to mention difficult.
Concrete board-mounted tiles are easier to remove, whereas concrete slab mounted tiles are a little more difficult.
Firstly don't forget to start with protective gear such as long sleeves and pants, gloves and eyewear to protect yourself from debris, and ear muffs if you are using electric tools.
You can either use a small sledgehammer or power tool to break up the tiles, then hire a power scraper that you can push along the floor to pry up the tiles.
Next get your hands on a chipping hammer, which is a bit like a small jackhammer. This will pulverise any remaining pieces of tile.
Finish the job with a handheld scraper and check the job for rough spots with a torch held parallel to the floor - this will light up any bumps.
Start by removing about a 12 inch tile area and chip out the grout with a putty knife and hammer, then pry up the board with whatever tools you have on hand.
Pulverise the board underneath with a hammer to expose the subfloor, pry up the entire board with tiles attached. If the board was fixed with screws then it will break into pieces and the screws will need to be removed afterwards.