How to turn off Wifi via ADB

Using "svc" through ADB:

Enable:

adb shell svc wifi enable

Disable:

adb shell svc wifi disable

Using Key Events through ADB:

You can use "keyevents":

adb shell am start -a android.intent.action.MAIN -n com.android.settings/.wifi.WifiSettings
adb shell input keyevent 20 & adb shell input keyevent 23

Using "adb shell", you can intent the android settings package and run the "wifi.WifiSettings" activity. From here we must then implement the key presses.

I tested those two lines on a Droid X.

Also, if you need to know more about "keyevents":

ADB Shell Input Events

to use those keyevents to toggle wifi in Android 5.0 you would probably have to hit different events then in answer. I would say  adb shell input keyevent 19 & adb shell input keyevent 19 & adb shell input keyevent 23  (the first one can be 20 as well) - this is working if there is no option selected when you enter the wifi settings screen (if there is, you should skip the first event)