With Luma, you can sell tickets to your events. Every so often, you'll need to issue a refund — if the guest can't make it, accidentally bought two tickets, or any other reason.
You can issue a full refund from the Manage Event page > Guests tab.
From the Guests tab, you can click on a guest and hit the "Refund" button.
If you'd like to do a partial refund, you can open their transaction in Stripe and do a partial refund in Stripe.