All Unbounce users can modify their own account settings at any time using the account menu accessed by clicking their User Name in the Unbounce Interface and clicking Manage Account.
To terminate your subscription, you can downgrade to the Free account level. At the free level you will not be billed, your pages will remain intact and you access your account at any time by logging-in in the normal way.
To downgrade your account go to the Change Subscription tab within the Manage Account page. Access this page by clicking your user name in the top right corner of the Unbounce Interface and clicking Manage Account. Then click ‘Cancel Subscription’ in the top right corner.
If you want to avoid being billed at the end of your free trial, just cancel your subscription before the trial ends.