I know there's a way to do it on a Windows, but unfortunately just have my iPad with me so can't go through it myself right now. And it's probably different on each version of a Windows. Argh...
This from Googling:
To delete a wireless network connection
Start Network and Sharing Center.
In the Tasks pane, click Manage wireless networks.
Right-click the connection you want to delete, and then click Remove network.
In the Manage Wireless Networks - Warning dialog box, click OK.
https://technet.microsoft.com/en-us/...=ws.10%29.aspx