This slot usually comes empty, in which case you still must perform this step. The SATA disk holder in your laptop is what you'll be removing then, and the process is the same, save for unplugging the disk from the motherboard.

Unplug the motherboard connection to the the SATA disk. You can do this either by unplugging it via the ZIF connector or by removing the SATA connector. My ZIF connector came out on its own when putting the SATA drive back in, so I'd recommend doing that anyway. Lift the little black latch up and to the right (as far as it goes) and then pull the wire out.

Unfortunately, I do not have good pictures of me unplugging the wire from this connector. You can find out how to work with ZIF connectors by clicking on the link above, or in the following steps, as there are plenty more of these to be found.

Unscrew the 4 M2.0 × 3.5 mm screws and lift the disk up and out of the laptop.