Hi and welcome.
Firstly, why are you removing it? Is it going back or are you wanting to get rid of it?
I know nothing about this sort of blind, but applying a bit of common sense, I'd suggest if you know who put it in, or can contact the manufacturer, ring their service department and ask them how you can do it yourself.
I presume behind the plastic trim there will be screws that attach it to the window frame. If it's not going back, these will show once the blind has been removed and you'll notice them every time you look out of the window, but if filled with some white silicone, six months down the line you'll have forgotten about them.