Within Teamwork Projects, you can edit an invoice, allowing you to change the details or remove items. 

To change the details of an invoice, select the billing area of your project.

Click the invoice you want within the left pane to view it then, hover over the invoice details to show the Edit link.

When you click edit, a modal will open where you can update the invoice details.

Note: A completed invoice cannot be edited.

In order to edit a completed invoice, you will first need to reopen the invoice.To reopen, uncheck the Reopen Invoice box at the bottom of the invoice, next to the export option.

For more information, see: Adding an invoice