Insert a spudger between the optical drive connector and the optical drive.
Twist the spudger to slightly separate the optical drive connector from the optical drive, then use your fingers to pull the connector away from the drive.
Lift the left edge of the optical drive slightly and pull it away from the right side of the outer case.
During reassembly, note that there are two holes in the optical drive face plate into which two stubby plastic posts must engage for proper positioning.
Great guide. I did this at same time as replacing my failed internal 1Tb Seagate hard drive (second disc factory fitted). All running great now.
I replaced my failed Sony AD-5680 superdrive with a compatible Hitach GA32N, only problem I had was that it was quite tricky to get the new drive in the caddy with the mounting srew holes lined up, needed a fair bit of pressure whilst lining up screws. Good gide - Thanks!