How to disable the shortcut Ctrl-Alt-Arrow in GNOME 3.8

The new keybinding you define in 'Settings-->Keyboard-->Shortcuts-->Navigation' will get appended to the previous/default one.

It will become, for example.

gsettings get org.gnome.desktop.wm.keybindings switch-to-workspace-down

['<Primary><Shift>Down', '<Control><Alt>Down']

I managed to remove the default keybinding using the following commands

gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-down "['']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-up "['']"

This clears all defined shortcuts for those tasks. And then just use 'Settings-->Keyboard-->Shortcuts-->Navigation' to define the desired shortcuts.

Source : https://bugzilla.redhat.com/show_bug.cgi?id=982695

In Ubuntu 18.04 Settings->Devices->keyboard in navigation search for shortcuts: super+up and super+down and change it, save in button define.

This worked for me on Ubuntu 12.04

Go to "System Settings -> Keyboard -> Shortcuts -> Navigation".

Find the workspace switching shortcuts bound to CTRL-ALT-ARROW. For each one of them do this:

Click on shortcut (so it says "New Accelarator..." allowing you to change the shortcut). Now Press 'Backspace' to clear it. It now says 'Disabled' for that shortcut.