You can cancel your account at any time. In order to cancel, just follow these steps:
Head over to your 'Billing' page on the left menu, under 'My Settings':
Then click on the 'Manage Subscription' button:
Finally, click on the 'Cancel Subscription' button.
This will remove your credit cards from the system, and your virtual numbers will no longer work.
If you wish to keep your phone numbers and transfer them to another provider, you can start a Port Out Request with your new carrier, and we will work with them to get your numbers transferred.