Edition: Professional, Business, Enterprise
User-level: Director and above
If you've cancelled an invoice, and now wish to delete it - you can do so by following the below steps.
Open the Project >Financials > Invoices tab
Open the cancelled invoice > click the ellipsis button at the top right > select Delete
Click Delete on the confirmation pop-up
Note: Deleting the cancelled invoice also removes the linked cancel credit for that invoice, and deletion is tracked in the project audit located under the Project menu > Details > Audit
That's it! Now you can successfully delete any (cancelled) invoice.