Go to Menu bar search for Keyboard in your Ubuntu Mint.
Click on Shortcut Tab on Keyboard Dialog box.
On Custom Shortcut vertical tab create one Add Custom Shortcut.
and in Keyboard bindings
Now you should have a new entry with your applied name and your keyboard setting. Every time you press Ctrl+Q your system will run the command /bin/false which basically does nothing. So this is a workaround to disable the setting.