You can cancel your subscription in the account at any time.
Please note that you can also lower the amount in your subscription very easily if you would like to spend less money on it per month.
You can find out how to do that in this article: "How can I change the amount of money (or CO₂) in my subscription?"
Step 1 Click on 'Account' > 'Account details' in your dashboard
Step 2 Select your subscription
Step 3 Click on 'Cancel Subscription'