You only pay for the items you choose to keep and the applicable fees (f.ex. shipping). If you return your entire order, you need not pay your invoice.
The amount for your return will be credited to your invoice. You can report the return to Klarna so that your invoice will be put on hold until we have had time to register your return. Report a return to Klarna here.
This only applies if you opted to pay by invoice during checkout. It does not apply to Apple Pay, Google Pay, PayPal or iDEAL payments, etc.