I would power wash it off.
Hi Martha, scrub the area with hot soapy water and rinse. Then apply vinegar to the area and let soak. You may need to soak a rag in the vinegar and apply it to the rust stains. Let sit for 10-15 minutes and then scrub again with a nylon bristle brush. Depending on how long the stains have been there, it may take 2-3 tries before you get them removed. Another thing to try is lemon juice which might work as well because of the acidity in it just like vinegar. Lots of elbow grease will help! Let us know if you conquer those rust stains!
Hi Martha, Pour or spray white vinegar on the rusted surface in place of lemon juice for tougher stains. Let the vinegar sit for several minutes before scrubbing it with a wire brush. Rinse away the rust with some cold water and repeat for difficult stains. Scrub the surface of the concrete with a brush. Rinse it well afterwards