Sure thing! You can cancel a Standardfan or Superfan Membership/subscription at anytime.
1) If you paid with Netbilling payment processor:
This will not end your access immediately. You will still have access until the end of your subscription period, and then at the end of your subscription month it will expire and you will return to being a non member.
2) If you paid for your subscription with Epoch/Paypal payment processor you can cancel your subscription by getting in touch directly with Epoch: https://epoch.com/
3) If you paid for your subscription with Bitcoin/Crypto currency your subscription will not automatically renew, so if you prefer not to continue with a subscription simply leave your subscription to expire after the month is up.
For 'Day Pass' users you don't need to cancel this subscription, as it is not a subscription but a one-off payment, that gives you 24 hours of access and then automatically expires. You will not be charged again.