@onestoptoys On the seller hub go to you Orders tab. Select All Orders. Locate the item you want to refund on (you can also use the search function at the top). Click the arrow on the drop-down to the left and you'll see "refund" - it's usually toward the bottom.
It'll bring up a page where you just enter the refund amount. At the top it will ask you for a reason and there's a chance to leave a note for the buyer.
“The illegal we do immediately, the unconstitutional takes a little longer.” - Henry Kissinger
"Wherever law ends, tyranny begins" - John Locke (Don't get distracted).