VoiceOver and Emoji and Symbols viewer VoiceOver uses Control-Command-Space for launching an action but I can't use it because Emoji and Symbols Viewer hijacks it. Is there a way how to disable Emoji and Symbols viewer?

I need VoiceOver more than emojis.
You can assign a different keyboard shortcut to the Emoji &amp; Symbols menu item. 

I usually add/remove a cmd, ctrl, alt or shift modifier when remapping menu items like this.

System Preferences > Keyboard > Shortcuts > App Shortcuts > + (plus button)