Visit the Manage Sub page while logged in with your Discord account.
Click the “Cancel Plan” button located in the “Billing & Payment” box shown below. (If you’re accessing the website from a mobile device, you may have to scroll down the page to find this section.)
Click “Confirm Cancellation” when prompted.
Your cancellation will take effect at the end of your current subscription period. You’ll keep access to all your plan’s features, including GPU time, until then.