Are you interested in removing the blank/Zip bezel below the optical drive's door or the optical drive's hinged door/bezel? The former can be easily done by pressing its release tab (located just inside the chassis interior, close to the optical/Zip drives carrier) inward and straight toward the front of the chassis. Once it pops out, you'll need to unhook the left side to remove the bezel. Removing/installing the optical drive's door/bezel is more time consuming. It involves removal of the optical/Zip drive carrier from the interior of the computer, the case's plastic upper handle and lower foot, and then the front bezel. After that's removed, you'll see (4) screws on the outside of the chassis that secure the optical drive door shield to the chassis. Remove them and reach inside to pull the shield away. Back on the outside, you'll see (7) plastic pins that protude slightly through the metal chassis. Push them back inward until they're flush with the chassis (a short wooden 1/4" dia. dowel is good for this). With one hand, push the optical drive door toward the inside of the computer, and grasp it from inside the computer with the other hand. Installation of the replacement is the opposite of this procedure.
By the way, I'd check eBay for the part, as many sellers part out the case components. Although "We Love Macs Money" is selling a new service part, the $35.95 price tag (like all of their pricing) is too much. You can certainly find it for less, such as here at eBay. You might even check any Apple Service providers in your area, to see if one may still have it in stock. While many of the repair shops won't sell parts directly to the customer, a shop having one in inventory may sell it to you, because of its age and the lack of demand for it.
