There's a built-in feature that will help you do exactly what you're asking about. :)
Try flipping the camera to the front. Then tap the camera case icon, right below the lens. And then hit the Edit Camera Bag button in the upper right corner.
From within this section, you can enable/disable lenses/films/flashes - using the + and - signs on the left. You can also re-order each item - using the three bar icons on the right.