Delete old networks from WiFi - "other networks"

I had a network when I had a router a few years ago. I no longer have this router nor network but it continues to show up on my wifi list under “other networks”. I can’t figure out how to delete it. I know it doesn’t hurt anything but I’m tired of seeing it.

Can it be removed from the Network Preferences pane?

Then in the advanced window?

No. I no longer have the password from this long ago network, so can never get it to show in advanced window.

Also, can prevent wifi from showing neighbor’s networks?