Remove baseboards or trim work around the room. Taking care when removing the trimwork allows it to be reinstalled when a new floor is installed after the tile floor is removed. Remove any appliances or built-in furniture like cabinets, if possible. Cover any vents with painter's removable tape and plastic to prevent dust from entering the ventilation system.
Break up the first tile with the blunt edge of a hammer (image 1), and then use a chisel to pry up the remainder of the first tile. Once this first tile is removed, place the chisel against the bottom edge of adjacent tiles, apply pressure with your hammer and the tiles should pop up easily (image 2).
Once the underlayment is gone, remove any adhesive with the flat edge of the flat shovel or a carpet scraper for large areas and a scraper or chisel and hammer for smaller areas. Clean up any remaining screws and adhesive using a broom and shop vac. The wooden subfloor should be completely smooth before installing a new floor.