In a small bowl, mix together the cumin, oregano, salt, pepper, and chili powder. Set aside.
Turn on the Saute function, and when the inner pot is hot, pour in the oil. Stir in the onion and cook until translucent, about 3 minutes. Add the garlic and cook until fragrant, about 1 minute.
Add the orange juice, lime juice, chicken broth, and the spice blend. Stir to combine. Add the chicken and press it down lightly into the liquid.
Lock the lid on the pressure cooker. Set the pressure valve to seal and cook for 5 minutes on high pressure. When the time is up, allow for a 10-minute natural release of pressure, then quick release any remaining pressure.
Remove the lid and shred the chicken with a fork. Allow the shredded chicken to soak up the cooking liquid.
Notes
If you prefer your carnitas crispy, spread the shredded chicken in a single layer on a greased baking sheet and broil on high for 3 to 5 minutes. Toss some of the leftover juice form the pressure cooker over the chicken when it's done.