Hi,
As per standard SAP, we can't hide the deactivated cost centers from the selection list.
Once we lock the cost center for postings, system will not allow for postings even though the cost center is in selection list.
We can do one thing, we can provide a report of Active list of the cost centers in the KS13 report. by changing the layout and setting filter as per the requirement.
Following Layout only shows the active list of cost centers
Regards,
Pavan Kumar Arvapally