Deletes this router & associated files (nvram, disks etc.)

def clean_delete(self):
        """
        Deletes this router & associated files (nvram, disks etc.)
        """

        yield from self._hypervisor.send('vm clean_delete "{}"'.format(self._name))
        self._hypervisor.devices.remove(self)
        try:
            yield from wait_run_in_executor(shutil.rmtree, self._working_directory)
        except OSError as e:
            log.warn("Could not delete file {}".format(e))
        log.info('Router "{name}" [{id}] has been deleted (including associated files)'.format(name=self._name, id=self._id))