Not able to cancel the Sales Order

Dear SAP Guru,

While cancelling the sales order I am getting an error saying ' Item 000010 can not be deleted because of subsequent document XXXXXXXX (This is credit for returns - billing document) as my client uses order reference billing for returns process. user have reversed the same billing documents but delivery number is not showing in document flow as they use delivery for stock reversal. attached docs for reference.

Please help me in cancelling the sales order as I am not able to delete it.

Thanks in advance..

Regards,