Unfortunately there is no Fade-out or Disappear command in Prezi which would allow to remove text or image from the canvas. However there still is a way this effect can be achieved. The trick will only work on a one-color background and it involves simply overlaying your graphic (text or image) with a small shape that is exactly the same color as the background.
So in order to make it work, you will actually need to use the fade in animation. The easiest way to achieve it would be to create a shape from the Prezi insert menu, because it can be resized to exactly cover your content: simply grab the edges and resize it. Also the basic shapes in Prezi can be customized via CSS which means you can make it any color you want.
However this will work with just about any random image that is the same color as the background (for example google black image, import it to Prezi and crop / move it to cover your content)
1) Add your content to the canvas.
2) Overlay it with a shape that has the same background color.
3) Animate In the shape using the Fade-in effect.
The only confusing part in this process can be that you won’t be able to see your text / image anymore because it will be covered. However I think this a small price to pay if you really need a Disappearing image in your Prezi 🙂