Please note that this may void your WD warranty. But if it's past your warranty or you simply do not care about your warranty, then proceed.
Please also note that disconnecting the fan may risk the device overheating. Upon disconnecting the fan, please place hard drive in a well ventilated area.
Step 1: Tool You Will Need
Remove all four screws on the outside case with Philips head screwdriver.
Step 2: Remove the Plastic Case
It should slide out like the picture shown.
Step 3: Unscrew the Metal Cover
Step 4: Removing the Metal Cover
Simply lift up the metal cover to remove it.
Step 5: Unplug Hard Drive
The remaining instruction is for disconnecting the fan. You will need to remove both hard drives.
Step 6: Removing the Fan
Follow the red and black wires from the fan into the case. I never bothered with trying to open up the rest. Rotate the case and try to look into where the hard drives were placed. You should see a white three-pin connector. Simply disconnect that and that should disconnect the fan.
If you're reading this step, I'm assuming you just wanted to disconnect the fan and will want to put the device back together.
Simply put the hard drive back in the order it was removed, connect the cables back on, slide back the metal cover (make sure the blue plastic piece on the hard drive sticks out from the metal cover), screw the metal cover back on, slide the plastic vent piece back in and re-attach the four screws from earlier.