The salesParm tables are used when posting sales packing slips, confirmations and invoices. Sometimes some lines with status error or waiting are left behind when there is an error during the posting process.
One of the options is to clean these lines is to use the 'Sales update history cleanup' in the Sales and Marketing module > periodic > Clean Up. With this option you can choose to clean finished update lines or error lines. Please use this option carefully and test it before use in a production environment.
Another option is to delete the lines for the specific sales order from the salesParm tables using the table browser in the AOT.