It has been a while since I removed any, but if I remember correctly, this is how I did it....
The blinds are held up by screws at the top that you can access by lowering the blinds all the way, then look up where the material is at the top. You might have to pull the excess material around a little to see them.
There is usually two screws that hold them up, one on each end appox one inch or more from the end. They screw thru the extra material and the frame at the top.
The screws take square drive bit. I have a 12" extension in a screwdriver that excepts the bits to make it easier to get to the screws.
Sometimes it feels like one has to stand on your head to access/see the screws.
If I lived closer I would be happy to show you where/how to remove them, but Ohio is a bit far.
If you really want to have fun, replace the string/rope that is in them.
I have done quite a few of them, first in our 5th wheel and two motorhomes.
Yep, the wife is really rough on them.....
Good luck with the windows. With two of mine I was able to get the windows from Gulf Stream and I installed them myself when the old ones seal went bad.
Ron