I say you don't even have to "kill" her. There's still a bit more you might be able to do with her tbh
For one thing, she's not vibing with the cast? Maybe there's personality traits in her that can be compatible with others in ways you may not have thought of. Maybe through her likes and dislikes of certain hobbies, morals even. If you've developed you characters far enough of to have lists of their interests, you might be able to make a connection between certain aspects and base chemistry off of that.
And if you can't be bother to develop her any further atm.. Maybe she doesn't need to be with them all the time, but she can still be an ongoing presence without her having to leave for some other location. If they have a home base they go back to all the time, you could have her spend her time there doing other beneficial activites outside of her powers, like being charge of communications or repairs but like just being basic at it.. Idk, seems worth considering