Windows Active Directory protects per default Organizational Units (OU) from accidential deletion .
To clear this flag for an entire OU structure you can use this Powershell commands . This example command will remove the flag from an OU structure OU=acme,DC=scom,DC=local and all child OUs .
sl AD:
sl "dc=scom,dc=local"
get-childitem -recurse OU=acme | where {$_.ObjectClass -match "organizationalUnit"} | Set-ADOrganizationalUnit -ProtectedFromAccidentalDeletion $false |