The blinds are clipped into 2 metal brackets. Raise the night and day blinds, then slightly press up the front side of the top rail. The back edge will come out of the clip. Disconnect the strings last. They help hold the shades up while you are getting the blind off the bracket.
Once the blinds are out, you'll see (S2 square bit) screws up inside the top of the valance. They are screwed into the cabinet above.
