Preheat a toaster oven to 375 degrees F and position a rack in the center.
Meanwhile, place the pitas on a toaster oven baking sheet. Brush the olive oil all over each pita.
Spread 2 tablespoons of the pasta sauce on top of each the pita. Evenly sprinkle each surface with 1 cup of the cheese. Sprinkle each with 1/2 teaspoon of the dried oregano then arrange 6 of the pepperoni slices on each pizza.
Bake until the cheese is melted and lightly browned, 5 to 7 minutes. Remove from the toaster oven and let cool for 1 to 2 minutes. Cut each pizza into 4 pieces and serve.