In a small saucepan, add peach preserves, mustard, soy sauce, chili powder and red pepper flakes over medium-low heat and bring to a simmer, stirring frequently.
Simmer for about 3-5 minutes, stirring frequently.
Remove from the heat and set aside.
Grease the Air Fryer Basket with cooking spray and then slide inside.
Adjust the temperature of Air Fryer to 380 °F to preheat for 5 minutes.
Season each chicken thigh with salt and black pepper lightly.
After preheating, arrange the chicken thighs into the greased Air Fryer Basket in a single layer and spray with cooking spray.
Slide the basket into Air Fryer and set the time for 18-20 minutes.
After 10 minutes of cooking, flip the chicken thighs and spray with cooking spray.
After cooking time is finished, remove the chicken thighs from Air Fryer and place onto a plate.
Brush each chicken thigh with peach glaze evenly.
Again, arrange the chicken thighs into the greased Air Fryer Basket in a single layer.
Slide the basket into Air Fryer and adjust the temperature to 400 °F for 2-3 minutes.
After cooking time is finished, remove the chicken thighs from Air Fryer and serve.