Yes. At any time, you may change your subscription plan through: Administration > Account > Subscription. Click on the Cancel My Account button on the bottom left of the Subscription page. Follow prompts.
Once cancelled, your account will be available until the end of your billing cycle. If you made an error you can reactivate the subscription from this page as well up until the end of your billing cycle.
If you change to a Basic/free account, your subscription will be cancelled.
Warning: Free accounts are automatically deleted if 30 consecutive days go by without a single login. We strongly suggest you set up a reminder for yourself to log into your free account every once in a while in order to avoid auto deletion.