http://www.thewindowsclub.com/forget-wireless-network-profiles-windows-10

Press Win+I to open the Settings app. Select Network & Internet. Next click on Wi-Fi in the left panel. There you will see a link Manage Wi-Fi Settings. Click on it.

In the window which opens, you will see two settings – Wi-Fi Sense and Manage known networks. Under Manage known networks, select the network, and you will see two options – Share and Forget.

Click on Forget. This will delete the Wireless Network’s profile and connection details.

You can also manually delete WiFi Network Profiles in Windows 10 using the netsh wlan  command in the Command Prompt or by editing the Windows Registry.

http://www.owenwebs.com/2015/08/16/windows-10-forget-wireless-network/

Open powershell: Press Win+R type in the run box: powershell and press enter

netsh wlan show profiles

This will provide you a list of all wireless networks your had your PC remember.
Now that you have your list,  identify the network you need to “Forget”.  To remove it type the following command in your PS window.

netsh wlan delete profile name="GuestHG"

change priority of wireless networks in Windows 10

http://mywindowshub.com/how-to-change-priority-of-wireless-networks-in-windows-10/

netsh wlan set profileorder name="GuestHG" interface="Wi-Fi" priority=1