E invoice for Credit Note if No quantity

I don't think that quantity is compulsory to fill while making an invoice, you can make it without quantity too.

1 Generate a new invoice:  Create a new invice with the same details as the original invoice, but with a cedit note type.

2.Zero quantity: Enter a zero quantity for the items being credited. 

3.Credit amount:Enter the credit amount (negative value) for each item.

4. Reason for credit: include a brief descripttion or reason for the credit note.

5.Reference to original invoice: with number and date

6. Verify and upload: upload the e-invoice to the GST portal.