The WiFi module is underneath a ribbon cable. To pull it back, flip up the white latch and it'll come right out easily. (Do not attempt to remove it without first lifting the latch).

I have no idea what module this. Device manager in windows says it's a Realtek.

To upgrade it or replace it, you just need to remove the black pad, unscrew the screw underneath, and disconnect the antennae. After that, it should come out like the m.2 drive.