Ntdsutil.exe is a command-line tool that provides management facilities for Active Directory Domain Services (AD DS) and Active Directory Lightweight Directory Services (AD LDS). You can use the ntdsutil commands to perform database maintenance of AD DS, manage and control single master operations, and remove metadata left behind by domain controllers that were removed from the network without being properly uninstalled. This tool is intended for use by experienced administrators. (Ntdsutil @ Technet)
First I will run below command to get all the domain controllers installed on the domain.
netdom query dc
Run below command to get FSMO role holders in a domain.
netdom query fsmo
Now open the command prompt with administrative rights and follow below commands to remove a crashed domain controller from the domain.
connect to server <other active dc name>
select operation target
select domain <number> (the domain number shows after above command)
select site <number> (site number shows after above command)
list servers in site
select server <number> (the dc number which is going to remove and appeared in above step)
remove selected server
Selected server removed from the server.