'Destroy a managed instance group.  This will destroy all instances
that belong to the instance group.
:param  manager: InstanceGroup object to destroy.
:type   manager: :class:`GCEInstanceGroup`
:return:  True if successful
:rtype:   ``bool``'

def ex_destroy_instancegroupmanager(self, manager):

    request = ('/zones/%s/instanceGroupManagers/%s' % (manager.zone.name, manager.name))
    self.connection.async_request(request, method='DELETE')
    return True
