Is there a way to turn down some of the options I chose during installation without reinstalling?
No, there isn't, because textures are re-generated completely so, even if we did an external utility to do the same, it would require to run after closing FSX, and it will take exactly the same time.
Since, of the total install time, 90% of it it's the textures regeneration, and that will be exactly the same even if there was an external utility doing it, it doesn't make much sense to write such program to do exactly the same thing the installer already does, to save you maybe 10% of the time needed compared to just running the installer.