But alcohol and lacquer thinner are easy to use on flat surfaces such as tabletops.
Simply wet some rags or paper towels with the solvent and lay them on the surface. Keep them wet by pouring on more solvent until the finish has liquefied and you can wipe it off with the wet rags or towels.
Almost all furniture and woodwork finished before the 1920s was finished with shellac, so use denatured alcohol on these. Almost all furniture and woodwork finished since the 1920s was finished with lacquer, so use lacquer thinner on these. If neither alcohol nor lacquer thinner dissolves the finish, use a paint-and-varnish remover.