Start by logging into your Parent account on my.codakid.com
You should see your Students tab at the moment. If you don't, click on the profile in the upper right hand corner.
Next, click the button that says "Subscription" to view your active subscriptions.
Now click the big red Cancel button.
After a small wait, you should see:
A subscription will almost always cancel into the Pending Cancellation status. That means the subscription still had some paid time left, and you will still have access to the courses until the end of the paid time. Cancelling a subscription does not process a refund for unused time.