How do I remove old vinyl from an existing wood floor?

http://homeguides.sfgate.com/remove-vinyl-tiles-adhesive-wood-flooring-36486.html

Start by pulling up as much of the linoleum or vinyl flooring as you can. Since it’s easier to work with smaller strips, it helps if you score the linoleum or vinyl with a razor knife into 12” wide strips.

You can speed the process by using a floor scraper to pry under the linoleum strips while you’re pulling on them. Once all the linoleum has been removed, it’s time to work on getting up the adhesive.

Remove Adhesive - There are chemical adhesive solvents on the market, but my concern is that they would soak into the hardwood. I would try working on small areas at a time by pouring boiling water on the adhesive and letting it sit for about ten minutes. Once the adhesive is loose, use a floor scraper to remove as much of it as you can.

Sand and Refinish Wood Floor - After the adhesive has been removed, allow ample time for the floor to dry. Once the floor is completely dry, rent a floor sander and edger to sand the floor smooth and remove any traces of adhesive.

Finally, vacuum up all the dust, wipe the floor down, and finish with several coats of polyurethane.

Pull up a corner and pour in some dish soap. A spot the size of a quarter will be enough, let it set for 2-3 min, if you are lucky the adhesive will turn into pudding. This means seriously soapy, I used DAWN, water will take up the flooring, it's just work after that. If the glue stays hard, I suggest you stick the tile back down and rethink the project. That glue is very toxic, very. Like HAZARDOUS WASTE bad news.