A family of Microsoft word processing software products for creating web, email, and print documents.
You should be able to unassign it.
- Select a U200C space in your document and open the Symbol dialog. The "zero-width non-joiner" will be selected (though of course it is invisible).
- Click Shortcut Key... The Customize Keyboard dialog will open with your shortcut shown in the Current keys box.
- Select that shortcut, and the Remove button will become enabled.
- Click that button to remove the key assignment.
Alternatively, you can open the Customize Keyboard dialog, select Common Symbols in the Categories list, select No-Width Optional Break, and then do steps 3 and 4.