Removing a Domain Controller

  1. Migrate DNS, DHCP, and any other services running on the older server.
  2. Migrate the global catalog.
  3. Migrate any operations master roles.  You can see who currently has the operation master roles with the following command on a domain controller:
    dcdiag /test:knowsofroleholders /v
  4. Run dcpromo on the domain controller that is going to be removed.