You’re best to email support if you want to close the account. See below picture for the email address.
However if you want to keep your account. Jump onto live chat and and request ALL devices to be logged out and change your password. Make sure to click “chat online” within the green box, don’t hit “get help quicker” as this is a bot.
https://help.nowtv.com/article/how-to-submit-a-complaint
Then put a payment PIN on your account, so nothing can be activated without your say so.
https://help.nowtv.com/article/change-pin-settings
