Compaq 500B Microtower Supplementary Manual page 18

6 Remove the side panel by lifting it away from the
computer.
7 Pull each of the three side tabs that secure the front
bezel to the computer, to release the front bezel.
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8 Swing the front bezel out to remove from the computer.
9 Locate the optical disc drives at the top front of the
computer.
10 Remove the screws that fasten the disc drive in the
computer.
Removing and Replacing an Optical Disc Drive