Remove the file named filename from the server.

def delete(self, file_path):
        """Remove the file named filename from the server."""
        if os.sep in file_path:
            directory, file_name = file_path.rsplit(os.sep, 1)
            self.chdir(directory)
            return self.session.delete(file_name)

        else:
            return self.session.delete(file_path)