You can't reset it.

Technically, you could run priority missions over and over, hoping to get the plot choices that offer a morality option (usually 15 or 25 points in one direction), but these are not guaranteed, and they're time-gated. It's a *long* slog.

So that's the bad news: you're kinda stuck there unless you want a long grind. The good news is that there really isn't an "incorrect" choice, including crusader. Sure, you might've chosen differently if you did it again, but the difference it will make in an optimized build is very low. Gear, sockets, perks, and passives will all have far more effect on things than morality (including morality items---which are generally lackluster in their current state).

Take my opinions as just that---opinions---but you're definitely not crippling your character by choosing one morality or the other.