Orphan Inter Domain Trust User Account

OK…all you AD GURU’s out there, here is my dilemma…
I inherited a small domain which it looked as it had tombstone a child domain and trust relationships that I was not allowed to delete. I used ntdsutil and was able to get rid of the child domain and the trust relationships so it looks clean. My problem is that the child domain had created a hidden user account named “ChildDomain$” in my case the child domain was called QA so the user is QA$. This account shows as system account and UserAccountControl 2080. No matter what I try I am not successful in removing this account. The Trust relationship is gone !!
How can I delete that user account??