I was wondering if it is possible to remove the portion of a soul inside a Horcrux without the person whose soul is actually in the Horcrux. I’m writing a Harry Potter fan fiction, and would really appreciate it if anyone could tell me.
It can be destroyed by damaging the Horcrux object past repair.
The piece of soul in Horcruxes can be destroyed, but the objects itself would have to be damaged beyond magical repair. It may remain somewhat intact, but it wouldn’t be “the same” as before the Horcrux is destroyed - it’d be at least some amount damaged, though possibly not totally ruined.
“That’s a problem we’re going to have to solve, though, because ripping, smashing or crushing a Horcrux won’t do the trick. You’ve got to put it beyond magical repair.”
- Harry Potter and the Deathly Hallows, Chapter 6 (The Ghoul in Pyjamas)
They were able to destroy the Dark Lord’s Horcruxes without his knowledge or consent, so this wouldn’t need the creator of the Horcrux to be present. The object needs to be damaged but doesn’t have to be completely annihilated - the Resurrection Stone in Marvolo Gaunt’s ring was cracked but the ring was still wearable and the stone remained in one piece despite the crack.