Correct, edit, adjust or cancel an approved work confirmation

Summary:

We created a work confirmation against a purchase order, but later realized that the confirmed amount entered in the work confirmation, was higher than the actual amount. We need to adjust the work confirmation to reflect the correct value. However, since the work confirmation has already been approved, we are unable to edit it. We attempted to create a new work confirmation with a negative amount to offset the excess, but the system does not allow this and prompts us to enter an amount greater than zero.

My questions are:
What are the available options to correct, edit, or cancel an approved work confirmation in Oracle Fusion?