Once you have removed the section of the case covering the hard drive, you will see a metal cover over the hard drive.

Remove the four 2.5 millimeter screws on each cover of the hard drive cover. (Be sure to have a safe place to put them, as they are small and are easily lost.)

Once you have removed the screws holding the hard drive cover in place, pull on the plastic tab until the cover comes off. The cover is on tracks, so be sure to pull horizontally in order to avoid damaging your computer.