I always just use a gel type stripper to remove any finish....shellac, varnish, lacquer, paint. Then wipe down with denatured alcohol or mineral spirits. Most strippers remove the finish with the first application.....then if you want to remove the stain too, a second application will do that.
I NEVER sand a finish off....destroys the patina & squares off the nice age-rounded corners somewhat. I come from a family of antique furniture restorers & believe me, this is the fastest & most thorough method.