To remove the optical drive, unlatch and remove the base cover. Unlatch and remove the front bezel. Then flip the front panel over to access the inside of the system. Identify the optical drive and disconnect the cables. Flip the front panel back over and unlatch the drive to remove it.
To reinstall the optical drive, slide it back into the system until it clicks. Flip the front panel over and reconnect the cables. Flip the front panel over to cover the system, secure the front bezel and base cover on the system.