'Detach the given disk from backing.'

def detach_disk_from_backing(self, backing, disk_device):

    LOG.debug('Reconfiguring    backing    VM:    %(backing)s    to    remove    disk:    %(disk_device)s.', {'backing': backing, 'disk_device': disk_device})
    cf = self._session.vim.client.factory
    reconfig_spec = cf.create('ns0:VirtualMachineConfigSpec')
    spec = self._create_spec_for_disk_remove(disk_device)
    reconfig_spec.deviceChange = [spec]
    self._reconfigure_backing(backing, reconfig_spec)
