If you are familiar with adding objects such as shapes, text boxes and pictures in a Microsoft PowerPoint presentation, then the design interface for Prezi will be intuitive. Despite the different effects with respect to animations and visual flow between the two presentation applications, the design mode features are more similar than they are different. Using layers and moving an element behind other visible layers, you can hide something without deleting it from your presentation.
Click on the element you wish to hide such that it is highlighted with the blue border. Alternately, you may click on another element that has a solid background, such as picture or a shape that is larger than the element you want to hide.
Right-click on the hand icon that appears in the middle of the element you selected. You'll see "+" and "-" symbols above and below the hand icon.
Click "Bring Forward" or "Bring to Front" if you are attempting to move an element higher in the layers to hide your unwanted element. Alternately, you can click "Send to Back" to send your unwanted element to the extreme bottom of the layer stack, which will effectively hide it assuming the top elements are larger.