The best paint remover for concrete depends on the type of paint. For example, oil-based chemical removers take paint off of concrete surfaces covered with oil-based paint. If you are unsure about the type of paint covering the surface, stick with the oil-based removers.
Concrete is a porous material that allows the pigments in the paint to soak below the surface. Once you apply the paint remover, it needs to remain in place several hours to loosen the pigments beneath the surface. Remove the substance from a small area using a wire brush or paint stripper. For larger areas, consider using a pressure washer to remove the paint.