Use your fingernail to flip up the retaining flap on the keyboard ribbon cable socket.

Be sure you are prying up on the retaining flap, not the socket itself.

Pull the keyboard ribbon cable out of its socket.

For reassembly, it can be helpful to put a small piece of tape on the keyboard ribbon cable (being careful not to stick any to the contacts), to create a small handle. Align the cable with the socket and gently pull with the tape to fully seat it.