For the past year the window has looked like this:
Since whenever I wanted to lower them, I end up with this:
This weekend I finally decided to do something about it. I wanted to trim down only the bottom third of the blinds since the fit on the top portion of the window was perfect.
First I marked which slat was the last one that didn't need trimming, and then I removed the entire set of blinds by opening the mounting bracket clip and sliding the headrail out.
At this point you could completely disassemble the blinds, remove the slats and cut them down. But I thought that was too much of a hassle. Instead I took the entire thing to my chop saw and carefully slide ONLY the slats that I wanted to cut down under the blade.
I needed to make sure that the slats I didn't want cut were clear of the blade. I used the laser guide on my saw to cut approximately a half inch off one end. (You may need to trim both ends of the slats depending on what obstacle you are fitting around, but since my change in length was so minimal, I didn't have to.)
Once cut, I reinstalled the blinds and tested to make sure they worked. You can see there is a slight length change, but it is barely noticeable. I think it would have looked worse if I had cut down ALL the slats since the gap between the blinds and the wall would be too large on the top part of the window:
And now, for the first time in over a year, I can shut the blinds again!