Removing tile adhesive is best done by drenching or soaking the adhesive with water, according to SFGate. Mastic, which is the most common organic compound in tile adhesive, is not water resistant. To remove excess adhesive after removing the tiles, soak several towels or cloths in water. Then, place them over the adhesive. Soak the adhesive until it becomes soft. After softening, scrape the remaining adhesive with a putty knife.
According to SFGate, do not use water if using set mortar for adhesive. The cement product is water resistant, but it is also brittle and comes up with the tiles during removal. Use a chisel, and pry the set mortar from the tile to remove large chunks of the adhesive.
If using vinyl tile adhesive, use a putty knife to scrape the material from the tile. Vinyl tile adhesives grow stronger over time, according to SFGate, so the more recent the tile was laid down the easier it comes up. If the vinyl adhesive cannot be removed with just a putty knife, use a heat gun or place an iron a few inches above the adhesive to soften it. If heat and water are not sufficient for softening the adhesive, apply a solvent to break down the glue to scrape it off.