Make sure that there are no termites left in the damaged wood. Use bug killer to eliminate any remaining termites before attempting any cover-up or repair job.
Use a chisel to scrape away dead wood from the termite-damaged area. If it is a thick structural beam, and there is enough good wood left for it to still be effective, fill up the damaged areas with wood hardener. Give it time to dry, sand any rough edges using sandpaper and paint the beam to hide any signs of termite damage.
Cut replacement pieces of wood if the termite damage is more extensive. For a supporting beam, it is best to cut another beam and bracket it to what is left of the existing support, using nails and screws, and then paint both beams to hide the damage as best you can.
Replace any other termite-damaged wood. Wooden flooring that has been eaten should be pulled up and replaced with new boards. Again, make sure there are no termites in the flooring before you put down new wood.