If you have a web subscription, you can manage a subscription from your parent account. Once you are logged into your parent account, go to "Settings" and you will see a button called "Manage" next to each of your child accounts with a subscription. With this "Manage" button, you can upgrade a subscription or remove cancel the subscription.
If you have a mobile subscription, you will manage the subscription from the general settings of your iPad. If you do not know how to do that, open up the settings for the iPad, scroll down until you see iTunes & App Store. Then, select the apple ID that you used to sign up for the subscription. When you get the pop up, select View Apple ID. Scroll down until you see subscriptions. Click on Subscriptions and it will show you your subscriptions. Find Tynker and you will be able to either cancel the subscription or change the subscription type.
Note: Removing cancelling a subscription removes auto-renewal from the account and does not cancel the subscription immediately. If you would like a refund for a web subscription, please contact us at firstname.lastname@example.org. If you would like a refund for an iPad subscription, you will need to contact the App store as we do not handle those purchases.