Remove the seven T8 Torx screws from the lower case.
Using your thumbs, slide the lower case toward the front of the computer.
The lower case may stick in the front on a tab just above the center of the optical drive. Be careful as you work the case off, or you may break the thin strip of plastic just above the drive.
Disconnect the pink and white inverter cable from the inverter board.
The display inverter has orange plastic shielding around it that looks similar to the tape used elsewhere within the computer. Do not remove the shielding from the inverter.
Depending on the new drive's model, the bezel on your old drive may not transfer to the new one. The bezel is not strictly necessary, and the drive will probably work fine without it, but you should transfer it if you can in order to ensure proper alignment with the case.
Remove the 4 Phillips #00 screws from the top of the optical drive.