If you have allowed a user delegate control permissions. For example, for the user to be able to modify groups but you now wish to remove the control, follow the instructions below:

1 ) Open Active Directory Users and Computers
2 ) Click View
3 ) Enable Advanced Features (If already enabled, you should see a tick)
4 ) Right click on the folder you set delegate control on
5 ) Click properties
6 ) Click the security tab
7 ) Remove the user/group
8 ) Click ok