File -> Preferences -> Keyboard shortcuts [Ctrl+K Ctrl+S]
is where you find those settings.
You can type the key combinations into the search field on that page as well.
Looking up Ctrl + Shift + C
shows a couple of commands, including Open New External Terminal which you are searching for. If you type "Ctrl + Shift + C"
, you get the two that have just this shortcut.
To get rid of it completely, just click it and hit Del
on your keyboard or use the context menu entry.
Or change it to another shortcut, it will tell you which shortcut you will overwrite then if the shortcut is already in use. In this case, a terminal can always be opened from the Linux desktop with Ctrl+Shift+T
anyway. Thus, just delete it, you will not miss the shortcut in Codium.