How to disable Ctrl+Shift+U in Ubuntu Linux?

Found a way to unbind it on Ubuntu 13.10.

Go to Language Support on System Settings and change the Keyboard input method system to none

Then restart the system or just log out and log in.

Problem

The problem is that with the "Ibus" input method, "Ctrl-shift-u" is by default configured to the "Unicode Code Point" shortcut. You can try this: Type ctrl-shift-u, then an (underlined) u appears. If you then type a unicode code point number in hex (e.g. 21, the ASCII/unicode CP for !) and press enter, it is replaced with the corresponding character.

Solution

This shortcut can be changed or disabled using the ibus-setup utility:

1. Run ibus-setup from the terminal (or open IBus Preferences).
2. Go to “Emoji”.
3. Next to “Unicode code point:”, click on the three dots (i.e. ...).
4. In the dialog, click “Delete”, then “OK”.
5. Close the IBus Preferences window.

Ubuntu 18.04 Solution

@ShmulikA's answer was close, but unfortunately, selecting "None" did not work for me. I can confirm the process below works in 18.04 as of April 2019.

1. Open Search using Super key (aka WIN for folks like me)
2. Type "language support" and hit ENTER

3. Click the Keyboard input method system dropdown menu and select XIM

4. Click Close
5. Reboot

When I logged back in, I was able to set CTRL+SHIFT+U as a shortcut in Visual Studio Code.