look where fpsc builds your game (standard is "mygame"-folder), open files/languagebank/english/gamebank/mygame, make copy of levelsetup.fpi (or something like that), then open original and delete the HUD-lines that you dont need.
to turn of the weapon-huds, you have to enter files/gamecore/guns, search your weapons there and exchange the needed dds-files with a blank pic (graphic-prog like photoshop, gimp etc. needed). there is no other way to turn it of, and there is no way to turn of the calculation-hud on the bottom. if its about screenshots, finalbuild your game, gives a much better picture.
