To remove the optical drive, identify and unlatch the base cover to remove it. Then unlatch and remove the front bezel. Find and unlatch the hard drive from the system. Identify the optical drive and unlatch it. Slide the drive out of the system.
To reinstall the optical drive, slide it back into the system and relatch it. Relatch the hard drive to the system. Place the front bezel and base cover back on the system.