It's behind the plastic where the green arrow is pointing to. Unless your hands are small, I found it easier to reach (and replace) after I removed the fuse box covers which are the 2 pieces covered in white sticky paper. Push the small triangular piece on the bottom towards the back and rotate it around to the right to get it loose, then you can push the tab clips (the bottom piece was covering one of them) to release the big top cover, one on the bottom and top side towards the front of the car to remove the big top piece. It WAS a bear to get it back in. You have to pop the top cover in first, then rotate the small bottom back over to where it goes. It has to slide over a ridge on the lower part of the big top cover.
Use a short flat blade screwdriver to get under the lip of the rubber grommet plug to pop it out.
