在子域自身出错无法降级的情况下，用ntdsutil手动删

1 删除子域域控

ntdsutil：me cl

          metadata cleanup: con

          server connections: con to do xx.com

            server connections: q

            metadata cleanup: se op tar

            select operation target: li si

            select operation target: se si 0

            select operation target: li do

            select operation target: se do 1

            select operation target: li se in si

            select operation target: se se 1

            select operation target: q

           metadata cleanup: re se se

2 删除子域

ntdsutil: me cl

metadata cleanup: con

server connections: con to se xx.xx.com（是server，不是domain）

server connections: q

metadata cleanup: se op tar

select operation target: li si

select operation target: se si 0

select operation target: li do

select operation target: se do 1

select operation target: li se in si

select operation target: se se 0

select operation target: q

metadata cleanup: re se do

3 如果删除子域出错，还可以用partition management 删子域

ntdsutil: Partition management

partition management: con

server connections: co to se xx.xx.com

server connections: q

partition management: li

partition management: delete nc DC=DomainDnsZones,DC=xx,DC=com

partition management: delete nc DC=xx,DC=com (这两行删除的顺序不能反）

4 去林根域控的DNS里手动删掉无效条目。

5 上文凡是0，代表列表中林根域或其域控，1代表子域或其域控。操作时必须仔细核对实际对应序号。