Step-By-Step: Manually Removing A Domain Controller Server

https://techcommunity.microsoft.com/t5/itops-talk-blog/step-by-step-manually-removing-a-domain-controller-server/ba-p/280564 

 Use of DCPROMO is still the proper way to remove a DC server in an Active Directory infrastructure. Certain situations, such as server crash or failure of the DCPROMO option, require manual removal of the DC from the system by cleaning up the server's metadata. The following detailed steps will help you accomplish this: 

 Step 1: Removing metadata via Active Directory Users and Computers 

 

 Log in to DC server as Domain/Enterprise administrator and navigate to  Server Manager > Tools > Active Directory Users and Computers   

 Expand the  Domain > Domain Controllers     

 Right click on the Domain Controller you need to manually remove and click  D elete   

   

   

 

 Click  Yes  to confirm within the Active Directory Domain Services dialog box   

   

 

 In next dialog box, select  This Domain Controller is permanently offline and can no longer be demoted using the Active Directory Domain Services Installation Wizard (DCPROMO)  and click  Delete    

   

   

 

 If the domain controller is global catalog server, in next window click  Yes  to continue with deletion   

 If the domain controller holds any FSMO roles in next window, click  Ok  to move them to the domain controller which is available 

 

 Step 2: Removing the DC server instance from the Active Directory Sites and Services 

 

 Go to  Server manager > Tools > Active Directory Sites and Services   

 Expand the Sites and go to the server which need to remove   

 Right click on the server you which to remove and click  Delete    

   

   

 

 Click  Yes  to confirm 

   

 

 

 Step 3: Remove metadata via ntdsutil  

 

 Right Click on Start > Command Prompt (admin)   

 Type  ntdsutil  and enter    

   

 

 

 You are then presented with the  metadata cleanup  prompt     

 

 Next type  remove selected server <servername> NOTE:  Replace <servername> with domain Controller server you wish to remove   

   

 

 Click  Yes  to proceed when presented with the warning window

   

 

 

 Execute the  quit command twice to exit out of the console