You can downgrade your membership to Pro or Basic Account Settings / Billing. Select Downgrade, then you will see the downgrade options on the Pricing page.
pricing
How can I upgrade to become a Premium member of Shoot The Frame?
You can upgrade to be a Premium member from the Pricing page.
Where can I find a tax invoice or receipt for my payments to Shoot The Frame?
You can find your tax invoices / receipts by heading to Account Settings / Billing. You can download or print your receipts.