To just remove the icon but still preserve workspaces
the output will be something like,
['application://nautilus.desktop', 'application://chromium-browser.desktop', 'application://ubuntu-software-center.desktop', 'application://ubuntuone-installer.desktop', 'application://ubuntu-amazon-default.desktop', 'application://UbuntuOneMusiconeubuntucom.desktop', 'application://gnome-control-center.desktop', 'unity://running-apps', 'unity://expo-icon', 'unity://devices']
To remove the workspaces icon from the dock you should just take out 'unity://expo-icon'
from that list. Taking it out, for this case the command should be:
gsettings set com.canonical.Unity.Launcher favorites "['application://nautilus.desktop', 'application://chromium-browser.desktop', 'application://ubuntu-software-center.desktop', 'application://ubuntuone-installer.desktop', 'application://ubuntu-amazon-default.desktop', 'application://UbuntuOneMusiconeubuntucom.desktop', 'application://gnome-control-center.desktop', 'unity://running-apps', 'unity://devices']"
(Don't forget the double quotes for the list on gsettings set
)
Best Answer
In simple words: you can't. By design, the launcher is intended to stay there always. If you want to give it up, the only way to do so is to give up the entire unity interface by switching to some other DE or by switching to the classic GNOME session.
Moving the launcher to some other edge of the screen is also not implemented and wouldn't be, as per Mark's comment on a bug.