When deleting an OAB public folder from Exchange Management console, you receive the following error: 0x80070005. This error means "Access Denied." You will still receive this error even if you use an account that has Exchange Organization administrator permissions. “You cannot manually create or manually delete an OAB root folder. When you create an OAB object in the directory via powershell or the Exchange Management Console, the owning information store will create the OAB root folder when site folder maintenance is run. When you delete an OAB object from the active directory, the information store will mark the OAB folder as unused during site folder maintenance. If it goes unused for 7 days, it is deleted by the store during site folder maintenance,” explained Dave.