To forget a Wi-Fi network from your list of available networks do the following:
You see a list of available Wi-Fi networks and saved Wi-Fi networks that are currently out of range.
Tip: Scroll down to go to the list of out-of-range saved networks.
Your device is disconnected from the Wi-Fi network.
Note: The Wi-Fi network still appears in the list, but your device will not automatically connect to it.