I want to change the paid status to unpaid

Hi there, pfamatrade!

You can unlink the payment to a bill or an invoice to make it unpaid. Just open the transaction, click the 1 payment made hyperlink under PAID, click the date to route you the payment page. From there, you can uncheck the bill or the invoice to unlink them.  The payment will remain as a credit in the vendor or customer's profile.

Alternatively, you can delete the payment transaction instead of unlinking it from the bill or invoice. Just do the same steps, so you'll be routed to the payment page. From there, you can click More and choose Delete, as shown above.

Let me know if you need help with your transactions. Have a nice day!