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

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.

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