Demoting a Domain Controller When Normal Demotion Fails If DCPromo fails to demote a Domain Controller gracefully, you can force the machine to forget it’s a DC by temporarily tricking it into thinking it’s a member server. Step 1 — Modify the product type in the registry Boot into Directory Services Restore Mode (DSRM) and open Regedit. Navigate to: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ProductOptions…