How to delete Organizational Units (OUs) in Active Directory 2012?
- Login to your domain controller with administrative privileges.
- Navigate to Start → Administrative tools → Active Directory Users and Computers.
- Click View on the menu bar, and then click Advanced Features.
- Navigate to the OU that you want to delete, right click on it and click on Properties.
- Click the Security tab → Advanced
- In Permission Entries, if the Deny entry option has been selected for everyone, remove it.
- Click OK to close the Advanced Security Settings.
- Navigate to the Object tab and uncheck the "Protect from accidental deletion" checkbox.
Now you can select the desired OU and delete it.