Hey, @loopzbr ! Welcome to Shopify Community!
Billing for your Shopify subscription happens at the beginning of your subscription cycle, and your first subscription cycle begins when the trial period ends. Since your store was still active when the trial ended, an invoice for your first subscription was generated in order for you to keep your store active. Outstanding invoices need to be settled before you can close and deactivate your store.
Since you no longer want to continue with your store, you have two options to proceed with to deactivate it. First, you can leave your invoice unpaid. If you miss paying your Shopify subscription bill or if a payment fails eight times, your store will be frozen after the last failed payment attempt. A frozen store is as good as a closed store. The other option is to settle the invoice and close the store. As mentioned by @AvadaCommerce we don’t provide refunds as per our Terms of Service, however, you may visit https://bit.ly/3cJkx8V and create a support ticket to request a refund and we’ll see if we can provide an exemption.