Ash here from the Shopify team. Welcome to the Shopify Community!
We have a page in our Help Center with steps on how to close a Shopify account. Before committing to that decision, may I ask what's driving you to want to close your store? If there are any roadblocks you're experiencing holding you from success, please let me know and I'll be happy to help out any way I can!
If you're certain that you'd like to cancel the account at this time, then the steps in the above document will walk you through the process. We guarantee to keep closed shops information on file for 30 days in case you wish to re-activate the account, but after that the account is subject to full removal from the platform. If there's any data or content you wish to retain from the account, I suggest checking out our documentation on Backups and Duplication.
With regards to money back, Shopify generally doesn't provide refunds as per our Terms of Service. With that said, I can absolutely take a closer look into your specific case to see if there's any possibility for an exception. I've sent you an email to the email address associated with your Shopify Community account. Please reply back to that email and I can take a closer look into your account.