Turn Keyboard Off?

Unfortunately, I spilled a drink on my macbook pro (2018) keyboard. The keys still work but they stick. So I bought an bluetooth Apple Keyboard. I'd like to turn off the built in keyboard so I can set the bluetooth keyboard on top of where the original keyboard is to make typing easier. I can't figure out how to turn off the original keyboard though.

I thought it would be System Preferences-> Keyboard -> Shortcuts ->"turn Keyboard access on or off". Alas, this does not seem to do anything at all that I can determine.

Please help!

(macOS Catalina 10.15.4)