You can undo the confirmation of a document that has not been sent yet to the ERP system by selecting the [Edit] option from the document’s context menu:
You can also undo the confirmation of such a document in its preview window by selecting the button in the top right corner:
After selecting the [Confirm] option, you can edit the document again. Then, if you select the [Save] option, the document will be saved as unconfirmed and will be assigned the Saved status in the document list.