Note: This only affects MD Settings which is currently scheduled for release in 58.

There is actually a way to remove a network from the list of known networks:
1. From Settings > Internet connection, click the > icon (or gear icon on older versions) to the right side of the network to forget.
2. Click 'forget' in the details subpage

Note: There is no way to 'forget' a non visible network; this seems like a problem with the design.

Also: There is no way to edit the properties of (or connect to) a non visible known network. (See  issue 543422 ). Previously we allowed navigation to the details page for known networks, but the current UX does not allow that.

@stevenjb, I agree there should be a way to delete known networks, not just preferred networks. I'll update the description and assign to Alan.

@bettes, can you look into this? One option "prefer" icon/button of some sort that moves networks to the preferred list, and a similar one for doing the opposite. I think when we discussed a star previously you were worried about users understanding what it means, but perhaps if it also triggers networks to move to the "Preferred" header it'll be clear.

bettes@ - Since this is a P1 I'm going to put it on my plate and will just implement something functional (and consistent with other UI) if I don't get any UX input :)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9279bfbd27957a1d6f23d0b86701dca726b53430

commit 9279bfbd27957a1d6f23d0b86701dca726b53430
Author: stevenjb <stevenjb@chromium.org>
Date: Thu Feb 02 21:19:22 2017

MD Settings: Internet: Convert 'Known Networks' page to dropdown menus

BUG= 680090 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2664383002
Cr-Commit-Position: refs/heads/master@{#447840}

[modify] https://crrev.com/9279bfbd27957a1d6f23d0b86701dca726b53430/chrome/app/settings_strings.grdp
[modify] https://crrev.com/9279bfbd27957a1d6f23d0b86701dca726b53430/chrome/browser/resources/settings/internet_page/compiled_resources2.gyp
[modify] https://crrev.com/9279bfbd27957a1d6f23d0b86701dca726b53430/chrome/browser/resources/settings/internet_page/internet_known_networks_page.html
[modify] https://crrev.com/9279bfbd27957a1d6f23d0b86701dca726b53430/chrome/browser/resources/settings/internet_page/internet_known_networks_page.js
[modify] https://crrev.com/9279bfbd27957a1d6f23d0b86701dca726b53430/chrome/browser/ui/webui/settings/md_settings_localized_strings_provider.cc

Verified on ChromeOS 9287.0.0, 58.0.3011.0