Soul Killing

Soul Killing is the ability to destroy the soul or essence of another being, mortal or magical.

Life Essences
The Life Essence Terra possessed a Businessman's body and later Piper Halliwell's. Their souls weakened as the possession went on. Terra explained that their souls would die if the possession went on. Terra killed the Businessman to possess Piper, who was later saved by Prudence and Phoebe.

Witches
Witches can destroy a ghost with the spell To Vanquish a Ghost and Return Him to His Rest, though the caster needs to be a ghost themselves for the spell to be effective. They can also use a potion for Banishing a Ghost when pouring it over the ghost's body remains. Prudence, Piper and Penny have used the spell on three separate occasions, and though the potion was made, it never had a chance to be used.

List of beings who use(d) Soul Killing
Original power Through spell, potion, etc.
 * Life Essences
 * Prudence Halliwell (Through a spell)
 * Piper Halliwell (Through a spell)
 * Penelope Halliwell (Through a spell)
 * Witches