Glitching/cheating **** i hate it. Where can i report cheaters/glitching **** in ranked matches.

(Glitch found in map Rooftops, you can sit inside a wall and shoot out of it. Why do you make the walls inside not bullet proof, is this so hard? then you can glitch whatever you like but its useless)

Here's the picture:
http://steamcommunity.com/profiles/76561197970959456/screenshot/542891019031719702/?