I recently made migration from Exchange 2003 to 2013 for two sites environment. For first site I have several DC’s and dedicated Exchange server but for second site (remote office) I installed only one Windows Server 2012 with two roles – Exchange 2013 mailbox and Domain Controller. Then I realized that this is not good idea and uninstalled both roles. During this I do not mentioned any problems – Exchange server disappear from directory and demotion of DC role of server passed normally – now it is not DC anymore. Nevertheless DC entry still exist in AD tree other servers are trying to replicate. I tried to promote and demote it again – same story (No errors from server but still exist in AD). I try to fix it with NTDSUTIL and ADSIEDIT but in both cases it gives me an error – Inisufficient rights and can’t remove it. I am using account that is member of all available administration groups.