In "Pay" on the left menu, you can find all your invoices, whether they are paid or not on Libeo.
Modify an invoice:
Click on the invoice you want to modify;
In the right panel, click on the leaf symbol with a pencil "Edit".
If you modify an invoice after the last accounting export, then a reversal will be automatically present on the next export.
Delete an invoice:
Click on the invoice you want to delete;
In the right panel, click on the trash can symbol "Delete";
If the symbol is greyed out and you cannot click on it, it means that a payment has already been made, thus you have to cancel it. Go to "Payment" below the main information and click on "Cancel".
Be careful, you won't be able to delete an invoice paid on Libeo.