One of the issues that I have come up against just recently is users not being able to delete or “Forget” a wireless network in order to change settings or Passkeys. This issue branches from the fact that “Manage Wireless Networks” menu has been remove with Windows 8.
However you can run the below commands to get that wireless network out of the way for you to create your new one.
Run the following from an admin command prompt.
First we need to check what networks we have with:
netsh wlan show profiles
This will give you a printed list of all wifi networks that you have configured, once you have found the one you want you can gather more information on it by using the following just replace NETWORKNAME with the name of your network:
netsh wlan show profiles name=NETWORKNAME key=clear
Now to delete said network just use the following command again replacing NETWORKNAME with the network you wish to delete:
netsh wlan delete profile name=NETWORKNAME
Now you are all set and can configure your network as normal.