First, remove the plate shown in the 1st image. If you've been following the guide, you should have already removed the screws holding this plate in place.

Simply, pull it off of the drone. It should come off relatively easy.

With the plate removed, you should see the 6 screws shown in the 2nd image. Unscrew and remove these screws.

With the screws removed, the bottom plate should basically just fall off on its own. DO NOT PULL IT OFF. The wire shown in the 3rd image is still attached, if you pull the plate off, you will break it. We do not need to remove the plate entirely so you can just leave it attached.