Follow steps below
1) In GameConfig.h
       change to  
       #define GAME_AUTOROTATION kGameAutorotationNone

2) InRootViewController.m commenting the following lines as
/*
#elif GAME_AUTOROTATION==kGameAutorotationCCDirector
    //
    // EAGLView will be rotated by cocos2d
    //
    // Sample: Autorotate only in landscape mode
    //
    if( interfaceOrientation == UIInterfaceOrientationLandscapeLeft ) {
        [[CCDirector sharedDirector] setDeviceOrientation: kCCDeviceOrientationLandscapeRight];
    } else if( interfaceOrientation == UIInterfaceOrientationLandscapeRight) {
        [[CCDirector sharedDirector] setDeviceOrientation: kCCDeviceOrientationLandscapeLeft];
    }
   
    // Since this method should return YES in at least 1 orientation,
    // we return YES only in the Portrait orientation
    return ( interfaceOrientation == UIInterfaceOrientationPortrait );
*/
3) In AppDelegate.m commenting these lines 
/*
#if GAME_AUTOROTATION == kGameAutorotationUIViewController
    [director setDeviceOrientation:kCCDeviceOrientationPortrait];
#else
    [director setDeviceOrientation:kCCDeviceOrientationLandscapeLeft];
#endif
*/
and add the following line of code
  [director setDeviceOrientation:kCCDeviceOrientationPortrait];
Done!!!! Now your app is on portrait mode..