Preheat the oven to 475°F. Spray a rimmed baking sheet or baking pan large enough to hold the legs in a single layer with nonstick baking spray.
Blend the olive oil, harissa paste, oregano, thyme, garlic, salt and pepper in a small bowl. Rub the chicken legs with the seasoned oil and place them skin side up in the baking sheet or pan. Bake for 40 minutes, until the skin is browned and crispy and the chicken is cooked through.
Transfer the chicken to a serving platter and cut the drumsticks and thighs apart if desired. Squeeze the lemons over the chicken. Serve hot or at room temperature.