The T15 screw marked in red is the last screw you need to remove before the left and right side covers can be removed

Slide the right black (or white) side piece ~5 mm towards the back to remove it. (The right side needs to be removed before the left; you will see an overlap of the sides at the rear centre.)

Then slide the left side back to remove it. The left side is slightly trickier to get on and off as you have to work around the water container inlet.

In the second picture I marked with red circles two of the many tabs that hold the sides in place. I broke and reattached a few of mine. I had no guide and I really wanted it apart so basically I got it apart the wrong way and then figured out the right way :o)