On the affiliate's Checkouts tab, tick the commissions, choose Mark as Rejected (or Mark as Unpaid) in the dropdown and click Update. Rejected commissions show a red badge and are excluded from the affiliate's balance; they can later be set back to Unpaid or Paid. Note that a commission already marked Paid cannot be changed, and refunding the underlying order does not automatically change the commission — review refunded orders and reject their commissions manually.