First you must install ProductivityPowerTools (it is FREE plugin/add-on):
For Visual Studio 2013 - DOWNLOAD IT FROM HERE: https://visualstudiogallery.msdn.microsoft.com/dbcb8670-889e-4a54-a226-a48a15e4cace
For Visual Studio 2015 - DOWNLOAD IT FROM HERE: https://visualstudiogallery.msdn.microsoft.com/34ebc6a2-2777-421d-8914-e29c1dfa7f5d
Then: Go to Tools->Options->Productivity Power Tools->Other Extensions
There is an option group called Structure visualizer options.
In there is a checkbox for Show code structure in editor. Turn it off and restart Visual Studio.
See the picture below:

Actually ProductivityPowerTools is a very nice addition to Visual Studio! :-) Here is one video explaining it's features (fraight from msdn.com :-) https://channel9.msdn.com/Events/Visual-Studio/Launch-2013/VS106
and another one from YouTube:
https://www.youtube.com/watch?v=fSGzTaUPH8o