Can I "Forget this Network" when the wifi network is not in range?

I have an iPod Touch that I upgraded to iOS 4 (but this an issue that also existed in iOS 3.1). When I travel, and I join a WiFi networks (e.g. hotel, etc), I don't always remember to forget the network before I leave.

iPod touch: Wi-Fi Information and Settings tells you to "Forget this Network" if you can choose it from the list of Wi-Fi Networks. However, when the network is not in range, you cannot select it to forget it.

Is there either a way I am not seeing in iOS to do this, or a third party application I can download? Does the fact I have extra WiFi networks in the list affect the performance of my device when it is trying to join known networks?

Update: I now have doubts a third party app exsits based on that Apple Drops Wi-Fi Sniffers from iPhone App Store reports "sniffers were dropped because they use a private framework, hooks in the operating system that are not documented nor allowed for third-party developers to use."

Solution 1:

Seems like no way to do this at the moment. Workaround:

The only solution seems to be to rename a spare access point to the SSID of the network you want to forget, connect to it with the iPhone, and choose the option to forget the network. This kludge seems like a lot of work and something that an average user probably doesn’t know how or want to do

via http://www.novainfosecportal.com/2010/07/08/forget-this-network-pretty-please/

Solution 2:

As user83905 pointed out, syncing your iPod and Mac with iCloud Keychain will enable you to manage both devices' remembered networks from either one. This means you can simply delete it from your Mac and the change will sync to your iPod.

If you do not have a Mac available to sync with, however, you can still forget unwanted networks by going to Settings > General > Reset and tapping Reset Network Settings. You'll need to add the networks you use again, but it will clear everything out so you can start fresh.

Solution 3:

IF you have a Mac: Sync your iOS device and Mac with the same iCloud Apple keychain. The wifi information will sync via iCloud to the Mac's keychain. You can then edit the keychain on the Mac, and delete the unwanted networks.

Solution 4:

You shouldn't worry too much as it only stores the settings (minimal storage impact), should you find a Wifi network with the same SSID, it may show up and ask you for the wap/wep passkey.