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.