Deleting an unfamiliar wifi network.

If you do not see it in your Network Setting simply ignore it or delete it from the list.

>System Preferences>Network>Advanced>WiFi

Select the Wi-Fi tab and view your Preferred Networks list.

1. Select each network and click the minus ➖ sign to remove those networks from your Preferred Networks list.
2. Click OK and close the Network preferences.

How to troubleshoot Wi-Fi connectivity - Apple Support

It is likely a network you connected to in the past and your device remembered it. Delete it from the list in preferences and if it does not reappear it is gone.

dylanmacdonald wrote:

Thanks but to reiterate: I don't want this network at all. I want it deleted. Where is it? How do I admin access it so I can delete it? I don't want to turn off SSID or delete it from an available network list. I want it removed. How do I do that?

Log into your Router and make changes

How do you know it is an open network—can you connect to it?

Log into your Router and make changes if necessary.

If a network is broadcasting its SSID then anyone can see it. This not not make it vulnerable, it makes it discoverable. If you don't want it to be discoverable log into the router and change the setting to not make it discoverable by configuring it to not broadcast its SSID.