My party killed asha during the escape

First time dming and i feel like out of the abyss is a challenge with so many npcs etc.

Yeah my players killed asha during the escape and i planned on pretending that they killed her and then later it would be revealed that she actually surviced, but one player decides that he wants to keep asha's head as a trophy.

Im not sure on how important she it to the story since i haven't read everything yet.