What will you do if you changed the server into DC, and you are assigned to locate the remote with slow WAN link? And it could be effective to remove AD from a server and what would you do afterwards?
If you change a server into a domain controller, then it will acquire the roles of a domain controller. Since the server is now the domain controller you will need to make sure that all the computers on the network are connected to it.
The computer will now be holding the operations master roles which have been designated to perform specific tasks so as to make sure that there is consistency and also to eliminate the potential for conflicting entries that may surface in the Active Directory database. The AD will be responsible for defining the operation master roles which will include the schema master, the domain naming master, the relative identifier master, the primary domain controller emulator, and finally the infrastructure master.
-Thompson Locker
