The domain was likely purchased and used on a previous Shopify account before you became the owner of the domain; however, when the previous owner of the domain closed their store, they did not remove the domain from their domain manager. To get this fixed up, we'll need to verify that you own the domain by having you provide a screenshot of your domain manager that shows the domain is under your GoDaddy account. I've gone ahead and sent you an email to provide a more secure method of providing this screenshot. Once you've replied there, I can help get the domain removed.
Sure thing! I have sent you an email. Please respond to the email with all of the requested information so I can help get this resolved.