The plastic cover is secured to the USB‑C port board with an alignment peg.

Insert the flat end of a spudger between the plastic cover and the top of the USB-C port board, above the 2.5 mm jack.

Twist the spudger to lift the alignment peg out of its slot in the board.

Pull the plastic cover off the USB-C port board.

Only the USB‑C port board remains.