The CD-ROM has to be pulled out straight up. Some force might be needed since the unit is plugged into the logic board at the bottom of the housing with a connector board (see the third photo). The board might come out with the CD-ROM unit, or still be connected to the logic board.

At the left side, it might be possible to use fingers to pull out the unit.

At the right side, a flat head screwdriver can be used. The force that is needed will most likely bend a metal spudger.

Once disconnected, flip over the CD-ROM unit and place it next to the housing with the logic board.

The brown cable will still be connected, optionally remove the one T9 Torx screw located next to the cooling fan (see second photo) to disconnect the connector from the housing.