To cancel your paid service, go to your account's "Billing" page. If you have monthly service, use the "Cancel Service" button. If you have yearly service, disable the "Auto renew" option. 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 this 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.