Felbook.Models.UserService.LeaveGroup C# (CSharp) Method

        public void LeaveGroup(User usr, Group grp)
        {
            usr.JoinedGroups.Remove(grp);
            grp.Users.Remove(usr);

            foreach (var subGroup in grp.GetAllSubGroups())
            {
                usr.JoinedGroups.Remove(subGroup);
                subGroup.Users.Remove(usr);
            }

            db.SaveChanges();
        }