Screenshot and other setting I think end up here in the global folder for specific settings.
C:\Users\Your Username Here\Documents\My Mods\SpecialK\Global\
I believe it’s achievements.ini specifically and the [Steam.Screenshots] section but renaming the files or even the folder should default it all. 
Hmm isn’t there some clear keybinding option or a way to force a empty or new choice like control or shift clicking, maybe something that could be useful if there’s no way to blank or default a binding?