ntdsutil roles connections connect to server <FQDN of role holder> quit seize schema master seize naming master seize RID master seize PDC seize infrastructure master quit quit
Use transfer keyword instead of the seize keyword, if the old DC is accessible
Open Active Directory Sites and Services, expand tree <site name> \ Servers \ <server name>
Open properties on NTDS Settings, and remove the tick from 'Global catalog' checkbox