Season chicken with garlic powder, oregano, cumin and salt and place in the bottom of the slow cooker.
Cover with salsa verde, cover and cook HIGH 2 hours or low 4 hours.
Remove chicken, shred with 2 forks.
Remove ⅔ cup of liquid from the slow cooker, and discard (unless you want it over rice).
Place shredded chicken back into the crock pot with remaining salsa, adjust seasoning to taste if needed and keep warm.
Season chicken with garlic powder, oregano, cumin and salt and place in the bottom of the Instant Pot.
Cover with salsa verde, cover and cook HIGH pressure 20 minutes. Quick or natural release.
Remove chicken, shred with 2 forks.