module.exports = {
    settings: {
        domain: 'your-domain.auth0.com',
        clientID: 'your-client-id',
        clientSecret: 'your-client-secret'
    },
    allow: function() {
        return false;
    },
};

module.exports = {
    settings: {
        domain: 'your-domain.auth0.com',
        clientID: 'your-client-id',
        clientSecret: 'your-client-secret'
    },
    allow: function(user) {
        return true;
    },
};

--- 
+++ 
@@ -4,7 +4,7 @@
         clientID: 'your-client-id',
         clientSecret: 'your-client-secret'
     },
-    allow: function(user) {
-        return true;
+    allow: function() {
+        return false;
     },
 };
Set default for allow method to be false
