To remove thinset from a concrete surface, use an electric chipping hammer, and for other surfaces, use a standard floor scraper to chip away at the thinset adhesive. To prep the area before removing thinset, cover furniture and other surfaces with plastic drop cloth to protect them from dust.
Tiles put in before the 1980s may have been laid with a thinset that contains asbestos. If the area could contain asbestos, be sure to have it professionally tested and removed. Concrete dust also presents a health problem, so use a dust mask to protect the lungs from harmful dust and fumes.
Once the tile is removed, begin to remove the thinset using an electric chipping hammer or floor scraper. Place the chipping hammer or the floor scraper at a 45-degree angle, and begin removing the thinset from the surface. Take care on surfaces like drywall so as not to damage the underlying surface. An angled grinder with grinding wheel can be used on concrete surfaces to get small patches missed by the larger electric chipping hammer.
After the thinset is removed from the surface, use a broom and dustpan or a vacuum to remove dust from the area, and clean the surface.