To provide one of your backers with a refund, head to your Backer Report from the Creator Tools menu. Click on the individual backer's name and select "Issue a refund." Once you enter your personal credit card information, you'll be able to issue a full or partial refund.
If you issue a refund within 14 days of your funding deadline, all fees will be refunded.
If a backer has been issued a full refund, it'll be reflected in your Backer Report. They'll no longer be able to post comments, but you can continue to communicate through messages.