A feature first released with the Windows Server 2008 Active Directory Users and Computers snap-in and included in the Windows Server 2008 R2 edition is an option to protect an object from accidental deletion. Setting this option defines a Deny permission to object deletion, so the result is not new, just the simplicity in configuring it is new. To protect an object from accidental deletion, perform the following steps of configuring this option on the Administrator user account:
1. Log on to the Windows Server 2008 R2 domain controller system with an account with administrator privileges.
2. Click Start, click All Programs, click Administrative Tools, and select Active Directory Users and Computers.
3. Select the View menu, and select Advanced Features.
4. In the tree pane, select the Users container.
5. In the right pane, locate the Administrator account, and double-click the user account to open the property pages.
6. Select the Object tab, check the Protect Object from Accidental Deletion check box, and click OK to apply the changes.
Source of Information : Sams - Windows Server 2008 R2 Unleashed