It was starting to rain, so I missed a few details with my picture-taking.
In each channel, there are three black brackets. You need to remove the front and rear bracket. You do not need to touch the middle bracket.
The rear bracket is easy to remove. Use a 10mm socket with a large wrench - they put lots of threadlocker on these.
To remove the front bracket, you need to remove this big sheetmetal piece over each front door. Use a 10mm socket to remove the two bolts. With this piece out of the way, you can get to the two nuts.
