Remove network names from "Choose a Network"

I want to remove (or delete) network names from my iPhone and my iPad that appear in the list "Choose a Network" when I am in Settings-->Wi-fi--> and have the option to select a network.

I have old network names that are showing up in this list. The wifi extenders are not plugged in so they are not even on. It seems the names are stored on the phone somewhere.

I can "forget a network" to stop using it as my current wifi connection and I can go to the list and select another network if I want to.

As for where the network names are stored, I have gone to Keychain Access on my iMac and deleted network names since I have iCloud and devices are synched. I've turned the synching off.

I have gone to the phone and the iPad ....Settings-->Accounts and Passwords--> here I have the options to:

-->App&Website Passwords to delete passwords for websites.

--> iCloud -->Keychain and turn it off.

I've delete things, but as the song goes, "the cat comes back the very same day."

I have also reset the network and I have turned the phone on and off and the router on and off.

Whatever I do, the old names of the wi-fi networks still are listed under "Choose a Network."

I looked at the router set up(192.168.0.1) and the old wifi extender names are not on the router anymore.

Bottom line, the names are in the phone and iPad somewhere....I'd like to get rid of old names and declutter.

Any suggestions?