in "Disabling the Bridge Script" of http://cylonjs.com/documentation/platforms/yun/
Edit the /etc/inittab file to comment out the ttyATH0 line (put a # before it)
::sysinit:/etc/init.d/rcS S boot ::shutdown:/etc/init.d/rcS K shutdown #ttyATH0::askfirst:/bin/ash --login
But I want to turn it on or off manually. Then I can program through WiFi if I want.
How to do that?