In your dashboard, go to Settings > Billing > Pricing Plan.
At the bottom of the page you'll find the following banner:
Just click on "Cancel Subscription Plan" and your subscription will be canceled.
You will be able to keep using the paid tools until the end of the subscription period, but there won't be any further renewals.
If you have any questions, please send us an email to firstname.lastname@example.org and we're happy to help.
Alternatively, if you want to downgrade or upgrade your plan, just select one of the options on the pricing table displayed in the same page.