Hello
On the standard system there is no option to delete COFC records, as it can lead to costing inconsistencies. However, under exceptional circumstances, for example, when the records are very old and they cannot be posted anymore, SAP can provide a report to delete those entries.
If you are sure that those records are no longer relevant and they cannot be processed anymore, you must open an OSS incident to SAP requesting this report.
Best regards
Caetano Almeida