Go to My Account > Billing (top right) > Cancel (and confirm)
Free 7 Day Trial: Cancelling within 7 days avoids any charges or payments.
3-Month Membership: You'll receive several emails notifying you in the final month of your membership, with a button allowing you to cancel. When you cancel, your access to the program will end at the conclusion of your current 3-month period.
If instead, you want more time to access the program, you'll have the option to continue on a heavily discounted 'Alumni Membership'. If you take no action, you'll receive an email to notify you 7 days prior to any auto-renewal charge.