Keep you soul methodHave a prethoryn fleet and move them to the Salvager Enclave, in their system and then pick the scrap a fleet option. Done.
Lose your soul method*** Spoiler - click to reveal ***To do this you need to have Bubbles, the Amoeba and have meet the Salvager Enclave.
To scrap you must get Bubbles to their enclave in their system and then pick the scrap a fleet option --> the Bubbles.
Doing so makes you worse then the entire xeno scum galaxy and your species deserves to be enslaved by the Prikkiki Ti, but hey you got this achievement....YOU MONSTER