To remove protection that prevents an OU from accidental deletion

1. Log on to the computer as a member of the Domain Admins group.
2. Open Active Directory Users and Computers.
3. Click View, and then click Advanced Features.
4. First, clear permissions on the OU for which you want to remove protection. To do this, right-click the OU, and then click Properties.
5. In OU Properties, click the Security tab, and then click Advanced.
6. In Permission Entries, select the Deny entry for the Everyone group, and then click Remove.
7. Click OK to close the Advanced Security Settings, and then click OK to close OU Properties.
8. Second, clear permissions on the parent container of the OU for which you want to remove protection. To do this, right-click the parent container, and then clickProperties.
9. In ContainerProperties, click the Security tab.
10. In Group or user names, select the Everyone group, and then clear the Deny check box for Delete All Child Objects, and then click OK to close Container Properties.