Open the windows in the room you are working in and put on rubber gloves. Pour mineral spirits in a small bucket. Saturate a paintbrush in the mineral spirits.
Brush the liquid directly on a small section of the tar paper until it is thoroughly saturated with the mineral spirits.
Scrape the saturated tar paper off the old floor with a putty knife. Wipe the putty knife clean with paper towels.
Repeat Steps 2 and 3 until you have removed the tar paper off the floor. Saturate any lingering tar paper with lacquer thinner and wait 10 to 14 minutes before scraping with a paint scraper.
Remove any lingering adhesive with a cloth dampened with acetone. Rinse the floors with a clean, damp cloth.