Manually remove DC from Domain

Open cmd console as a Administrator in Enterprise Admins group

cmd> ntdsutil

metadata cleanup

connections

connect to server DC01

quit

Select operation target

list domains

select domain 0

list sites

select site 0

list servers in site

select server 1

quit

remove selected server

quit

quit

Refer Site

Using the NTDSUtil tool First, open the command line or PowerShell with administrator privileges. Type ntdsutil and press Enter. Type metadata cleanup and press Enter. Type connections and press Enter. Type connect to server <-servername> and press Enter. Where <-servername>, is the name of a working DC in the same domain. Type quit and press Enter. Type select operation target and press Enter. Type list domains and press Enter. Type select domain <-number> and press Enter. Where <-number>, the corresponding number to the domain that the non-functional DC member was a member of. Type list sites and press Enter. Type select site <-number> and press Enter. Where <-number>, the number that corresponds to the site that the non-functional DC member was a member of. Type list servers in site and press Enter. Type select server <-number> and press Enter. Where <-number>, the number that corresponds to the DC you want to remove. Type quit and press Enter. Type remove selected server and press Enter. In the confirmation window that appears, click Yes to continue the deletion process. Finally, type quit and press Enter to exit the NTDSUtil management environment. After completing the steps above as you like, do not forget to check all DNS objects to delete any records of the removed DC.