Set your Instant Pot to the sauté function according to your manufacturer's instructions. Add the butter and allow it to melt completely. Once melted, add the chopped onion, carrots, and celery. Sauté for about 3 minutes until the onion is softened and translucent.
Season the sautéed vegetables with salt, pepper, dried thyme, parsley, and oregano. Add the chicken bouillon and stir to combine.
Pour in the chicken broth, then add the chicken pieces. Add 4 additional cups of water.
Secure the Instant Pot lid, following the manufacturer's instructions for proper sealing. Select the "Soup" setting and set the timer for 7 minutes. If your Instant Pot does not have a Soup setting, use the Manual/High Pressure function for 7 minutes.
Once the cooking cycle ends, allow the Instant Pot to naturally release pressure for about 10 minutes. If pressed for time, use the quick-release method according to the manufacturer's guide. Carefully unlock and remove the lid.
Take out the cooked chicken pieces and shred them with two forks.
Return the Instant Pot to the sauté setting. Add the uncooked egg noodles to the broth and cook uncovered for approximately 6 minutes, or until the noodles are tender.
Turn off the Instant Pot by pressing the cancel button. Return the shredded chicken to the pot, stirring to combine. Taste and adjust seasoning as needed. Garnish with extra parsley, if desired.