If they don't have soul destruction, they can't perma-kill her, as she'll just come back.
That said, whoever said you need to kill her, in order to put her down? Not like she's actually capable of doing anything to most opponents peeps stupidly(or spitefully, for the lols, like @Masterblack06 just did) put her up against, anyway.
Actually, due to how the Brother God's Curse works, just mind controlling her into accepting that Life and Death's true meaning is more than enough to break it and thus kill her for real.
She literally got incapacitated by an explosion never mind soul destruction tossing her into a constantly matter destroying substance should deal with her
It's funny people bring up her staying conscious jumping into the Grimm Pool but then she gets incapacitated by virtual Hollow Purple 200% and is out for hours lol.