Frugl Grocery uses social media networks for authentication where supported for the convivence of users and to ensure that Frugl Grocery does not hold any record of User Passwords that could put a user security at risk if a data breach did occur. While you can request your user information is removed from Frugl Grocery application servers by contacting support directly Frugl Grocery does not have the ability to modify your Facebook permissions for applications.
To remove an Application from your Facebook account please follow the instructions as provided by Facebook – https://www.facebook.com/help/170585223002660