How do you clean up tung oil that has dried on a concrete porch
Caustic soda.
Sprinkle on and dampen to a paste, cover with newspaper and plastic sheeting.
allow to sit several days, sweep off, scrub,  and rinse off with plenty of water.
Danger: corrosive: Keep away from aluminium, Wear water-proof gloves and eye protection.  Wash with water without delay if you get any on you.