It may happen that you've accidentally uploaded a purchase invoice as a receipt. If that's the case, you can easily move the purchase invoice to the purchase invoices section. However, this can only be done if the document has not yet been processed.
To move a document from receipts to purchases invoices follow the steps below:
Navigate to Expenses in the left-hand menu;
Choose Receipts;
Select the documents you want to move;
Click on Select action and choose Move;
In the pop-up choose in the Action dropdown for Move to purchases;
The document(s) has now been moved to the purchase invoices.