Information
This configuration causes an iOS device to forget Wi-Fi networks with which it has previously associated. It is recommended that networks be forgotten after each use in use cases where security is paramount.
Solution
On the iOS device,
1. Tap Settings.
2. Tap Wi-Fi.
3. From the Choose a Network list or from the active network listing, locate the network SSID and tap the Detail Disclosure button next to the Wi-Fi network you want to forget (see note below).
4. Tap Forget this network.
5. Tap Forget on the confirmation dialog.