64 bit build iOS in Unity free

we built a game using Unity 4.6, and we are not able to do this http://docs.unity3d.com/Manual/iphone-64bit.html.

Does anyone know if we need to upgrade to Unity Pro in able to launch on iOS devices?

Yes, I believe that you need the professional editor of 4.6 in order to build for iOS. You can upgrade to Unity 5.1 though, where the free personal edition allows you to build for iOS.