Get an old bath towel or something and lay it on the wax. Take a clothes iron and run it across the TOP of the towel. As the wax heats up, it will get absorbed into the towel. DON'T reuse the towel on a 2nd spot, or for a 2nd time, because you'll reheat the wax and 'lay' it back down on the concrete. Cut the towel up in many pieces and use them one at a time. Do manually 'pick' at the hardened was as much as you can before you use the towel and iron.