Time to remove the majority of screws from the casing. Depending on what you're trying to accomplish, you may not need all of them. But for the sake of this guide, let's assume you do

On the outside of the bottom casing, we have 10 screws, all the same size

Inside the unit there are 4 normal screws

There are 2 black, large-headed screws inside the hard drive bay on the left