2008 - How to demote one domain controller from an existing domain

If you have different domain controller and you need to dismiss one you can follow this procedure:

1. Verify with this command that DC hasn't any 5 AD Role (cmd executed as Administrator):

netdom query fsmo

2. start --> run --> (executed as Administrator) DCPromo

2008 Server - Remove a Windows Server 2008R2 DC from an existing domain