To cancel your paid service, go to your account's "Billing" page. Then, use the "Cancel Service" button. Your account will no longer automatically renew and your paid service will end at the end of your current billing cycle.
When paid service ends, nothing is deleted. Your account will revert to the Free level and you can continue at that level for as long as you want. You can leave your account inactive (no logins or form activity) for a maximum of one year before it's considered abandoned. Abandoned accounts may be permanently deleted.
You can upgrade your Free account back to paid service at any time to pick up where you left off.