Error Line Printed, cannot change this line
Cannot delete item line during Point of sales (POS) transaction.
Causing
This is due to the line you wanted to delete is already printed at physical receipt.
Solution
To resolved this error, you can login to POS > more function > Configuration setting > Receipt Tab > tick Print receipt after made payment.
Tick Print receipt after made payment.
After you done above setting this should be solved your problem. For more info, please refer to detail.