Go to Facebook Help Center>Apps>Manage Your Apps
Follow the guideline given for removing an app that was added.
(URL: https://www.facebook.com/help/170585223002660 )
Go to Google My Account>Apps with account access
You can remove the apps on that page.
(URL: https://myaccount.google.com/permissions )
* The information above is to remove the connection with SNS ID and does not concern closing your account.