I know of a way to remove a dent in the floor, but it may damage the finish. A combination of heat and moisture can sometimes remove a dent of the type you have. Place a moistened paper towel over the damage and hold a medium hot iron on the folded paper towel. The goal is to use steam to force moisture into the wood and cause the compressed wood fibers to expand back to their original shape. I have used this method to repair dents in unfinished wood with success, but I do not know how it will affect the finished floor.