You can move an invoice to trash in Moon Invoice easily by following the steps below.

1. Open the Moon Invoice application on your device or tap on this link.
2. From the main menu on your left, go to Sales ➜ Invoices.
3. Click on the existing invoice, then on the right-hand side, click the three-dot icon (⋮) and select Trash.
4. A confirmation pop-up will appear, where you can click Yes to proceed. 

Note: You can also delete an invoice by directly clicking on the Trash option located just above.