Question : Delegation to a group must be removed

Goodmorning,
We have delegated a group to join computers to domain but, now, we need to remove that permission from every object.
I've tryed to deny writing permissions on that OU, but i see that they still have permissions to join old computer names to domain (wich were delegated to them.
Maybe with a script to remove this group from every computer object ? Exsists? Or there is something about permissions that could allow me to.. deny them? :)

Answer : Delegation to a group must be removed

Sorry, as told "we need to remove that permission from every object", not just from the OU.
I've found a way by myself, using

DSACLS "ActiveDirectory Object DN" /R "Domain\GroupName"

However, thank you ;)