This has definitely come up before. We even wrote an article about it here. In short, you can't change a domain registration once it has been completed. You only have the option of canceling it and registering a new domain. You can usually get a refund if a new domain is canceled within 5 days of registration. You're going to need to get with our support team for the refund anyway though, so I suggest giving them a call when you are able to do so.
JesseW - GoDaddy | Community Manager | 24/7 support available at x.co/247support | Remember to choose a solution and give kudos.