The cost center standard hierarchy should represent your company’s structure and be what you use most often in your reporting. This is because the standard hierarchy, which is guaranteed to contain all of the cost centers in a controlling area, is easily maintainable
You can maintain cost center standard hierarchy with transaction OKEON or via following SAP menu path.
Accounting->Controlling->Cost Center Accounting->Master Data->Standard Hierarchy-> Change
You can drag and drop cost center to different hierarchy nodes as your organizational structure changes. The standard hierarchy is really special cost center group that contain all cost centers.
You can only maintain the standard hierarchy or groups within the standard hierarchy with OKEON SAP Transaction code. You can create as many alternate hierarchy as you need for reporting purposes you can maintain these with KSH2 Transaction.