Windows 8 users can remove the unused Wi-Fi connection from their connected network list using the Forget this network option.
Step 1: Click on the Wi-Fi icon on your Windows 8 taskbar, if Wi-Fi icon is not displayed on the taskbar then check the hidden icons list.
This should display the Wi-Fi networks list screen as shown below
Step 2: Now right click on the Wi-Fi network that needs to be removed and choose Forget this network the menu list.
This would remove all the connection settings associated with that Wi-Fi network from your Windows 8 system.