Why is there a Secondary Air System?
To allow addition of airbox air to the post-engine exhaust before the catalytic convertor in the stock exhaust.
Why is it on my bike?
The stock exhaust has a catalytic convertor - and the bike comes with the stock exhaust.
Why get rid of it?
Some don't like the idea of another electronic thing that can choke your bike leading to stalling issues/inoperability. Also, some FI maps may not even sense it hence there's no point for it (I'm not 100% sure on which ones). Lastly, if you change the exhaust and no longer have a catalytic convertor - you don't need an SAS.
I took it off because I could and because it cleans up the area under the airbox - oh, and because of the exhaust change.
The SAS valve is prominent on the LHS of the bike under the LHS side panels and connects to the top of the engine and the bottom of the airbox. You've undoubtedly noticed the connection when removing the airbox for any work.
You could probably do this without removing the airbox but I have banana-hands and not lady-fingers so I had to. Remove the SAS valve assembly and follow the hoses to the airbox and engine - disconnect the hoses at both points. Unplug the SAS valve from the wiring harness, now throw it under a train.
Using the stock circle clips, attach 1/2" ID vacuum plugs at the airbox and engine head.
Once you've discarded all that tubing and the SAS valve, you will need to splice the 22k Ohm 1/4w resistor into the plug wiring as above with the total canisterectomy. I cut off the plug, trimmed some of the excess wiring and installed quick-disconnects as above to enable easy reversal. Same dealio with the adhesive shrink wrap and electrical tape overload.
Now you have more room to route wiring for more farkles and less criss-crossing tubage.