Remove all the files listed in filenames.

def remove_files(self, *filenames):
        """Remove all the files listed in filenames."""
        filenames = list_strings(filenames)

        for dirpath, dirnames, fnames in os.walk(self.workdir):
            for fname in fnames:
                if fname in filenames:
                    filepath = os.path.join(dirpath, fname)
                    os.remove(filepath)