When domain controllers are taken offline without being demoted first, the domain metadata is still left in Active Directory. This article illustrates how to remove that domain metadata with the help of NTDSUTIL utility.
Open PowerShell with elevated privileges and execute the following commands in sequence.
Step 1. Type ntdsutil and hit enter from keyboard
Step 2. Type metadata cleanup and hit enter from keyboard
Step 3. Type connections and hit enter from keyboard
Step 4. Type connect to server
Step 5. Type q and hit enter from keyboard
Step 6. Type select operation target and hit enter from keyboard
Step 7. Type list domains and hit enter from keyboard
Step 8. Type select domain
Step 9. Type q and hit enter from keyboard
Step 11. Ignore the warning and click Yes
At this point the domain should have been removed. You can quit ntdsutil utility. If you would like to remove more domains, go back to step 6 and start the whole process again.
