ARE YOU KIDDING ME?!?!?! THIS EFFING EMPEROR!!!
even if MC doesn't want/can't kill Yuriel, she can definitely make her wish she was dead, hell, at the very least she can send her to the most isolated job post so that she can have no interactions with other people!!! Keeping her as a maid, even if to keep an eye on her, is just letting her go around doing whatever she wants!