Question : NTDSUtil.exe tools

We add new AD on the same forest2 into our infrastructure and decided to do separate forest, our admin remove the 2 DC unsuccessfully now there is a remains into the original AD. we have to clean it up using ntdsutil tools. can anybody provide me with the step by step procedure and what is the risk of doing this.

Answer : NTDSUtil.exe tools

yea, the risk is that you will remove a DC that's still online by mistake.  If that happens you may have to seize FSMO roles and demote and re-promote that DC.