If you want to delete all zones and clear all the past watering activities, you can do a factory reset.
1.Power off the device(unplug the power adapter)
2.Wait for 2 seconds, replug the power back in
3.Wait for 3 minutes for the device to start up
4.Press and hold the reset button for 8 seconds to do a hard reset
5.Wait for 3 minutes. This should set the light to slow blinking.
6. Then you can go to the Netro app -> settings-> controller -> change wifi network/password