Remove (Demote) a Domain Controller
Two paths to remove a Domain Controller from Active Directory - graceful demotion via Server Manager (Remove Roles and Features wizard) for an online DC, and manual / forced removal via ADUC delete-from-Domain-Controllers-OU for an offline one. Walks both paths end to end with the actual screenshots. Includes the FSMO transfer pre-flight, the Test-ADDSDomainControllerUninstallation cmdlet, the post-demote AD Sites and Services cleanup, and a one-shot DNS scrub script that removes A/NS/SRV/CNAME records for the demoted DC across every Primary forward zone in one pass.