STEP 1. First you have to open Finder Window.
STEP 2. Now under the “Devices” section on the left you have to choose your hard drive.
STEP 3. Now you have to go to /System/Library/Core Services/ Menu Extras
STEP 4. Within Menu Extras directory you can find Eject.menu file.
STEP 5. Now simply double click on the Eject.menu file to add an Eject Button to Mac OS X Menu Bar.
That’s it. You have successfully added Eject button to your Mac OS X Menu Bar. If you want to remove Eject Button from the Menu Bar then simply Press and hold the Command key, then Click and drag the Eject icon and when you see no Eject menu appears in the Menu Bar then release the Eject icon. If you found any difficulty in following the above steps then feel free to ask in the comment section below.