Update 2018 - Prezi Next now fully supports fade out animations so you can make objects appear and disappear.
Prezi offers a great Fade-in effect for all texts and images, however the most common request from the Prezi users is also a Fade-out effect which would make objects disappear the same way. Unfortunately Prezi does currently not support this but maybe due to high demand, the feature will some day be implemented. At the same time there is already a little trick you can do to make your text disappear in Prezi:
The key to achieving the disappearing effect lies in the background of your Prezi and the background of the specific text. You can only make text disappear by overlaying it with a small graphic element (e.g. Shapes from Prezi Insert menu) that exactly matches the color of the background. If you are using a 3D background then this trick won’t help because the image would move unproportionally in relation to the background. The Prezi shapes are good for overlaying texts, because they can be customized to match any color and size. Click here for a tutorial about editing Prezi shapes.
Watch the example video on how to make text disappear on a black background:
