Dip a steel wool pad in denatured alcohol.
Apply the steel wool to the floor, rubbing it in a circular motion. Work in small sections, as opposed to trying to tackle the entire floor at once.
Wait for the shellac to loosen on the floors. The time required will depend on how much shellac is on your floors and the specific product used. When in doubt, test a small area by wiping the floor with a rag or clean steel wool to see if the shellac comes off.
Use a flat tool, such as a putty knife, to scrape up the shellac in stubborn areas or in corners difficult to scrub by hand.
Apply a solvent, such as alcohol, to the floors after the shellac is removed to get rid of any grease left behind by the steel wool.