IPhone : Dismissing a modal view controller via code

iPhone project/iOS 7.1/objective-C Due to circumstances, i have presented a navigation controller which contains a view controller which in turn contains a web view.All of the before said are added programmatically (i.e. no .h,.m or xib files).How do i dismiss the navigation controller?

P.S: I've created all these in a method.There is no property or instance available for the navigationcontroller.