How to Cancel Subscription
https://support.na.square-enix.com/f...22&id=496&la=1

How to Cancel Account
https://support.eu.square-enix.com/f...20&id=612&la=2

While I've never done either of these things, hopefully these links and the other posts are enough to help you out. Just to be on the safe side I would cancel the subscription before I canceled the account. Best of luck!