I'm not a PS4 guy, but I'm 99% sure this won't work in "newer" PS4 firmwares. It used to be that PS4 only remembers one wifi network, so if you switched to another, it'd forget the first.
But a while back they did update the firmware and now it remembers multiple networks, BUT does not provide a UI to forget previously remembered networks, apart from resetting the whole console to default settings.
Sheesh. What a piece of work!