老是提示什么物理网络被使用之类的，
可以进数据库去直接删除。
I want to delete a zone,by this way:
(1)delete all VMs in zone.
(2)delete primary storage.
(3)delete host in cluster.
(4)delete cluster,delete pod.
(5)delete secondary storage.
(6)delete physical network.But in this step,failed.
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I have ran into something similar.
Removing things is just a real pain in CS (at least from my experience)
In the mysql cloudstack DB there is a table called physical_networks you could try removing it from there.
