After you add a photo or graphic to your document, you can crop it and remove parts you don’t want.
You can hide unwanted portions of an image without modifying the image file.
Double-tap the image.
The mask controls appear. The default mask is the same size as your image.
Use the controls to change which parts of the image are visible:
Tap Done when you’re finished.
Double-tap the image at any time to readjust its mask.
Use the Instant Alpha tool to make parts of an image transparent. This feature is useful for removing an unwanted background or color from an image.
Tap the image, then tap 
.
Tap Image, then tap Instant Alpha.
Drag your finger over the color you want to disappear.
As you drag, the selection grows to include areas that use similar colors. Tap and drag multiple times to remove multiple colors.
Tap Done, or tap Reset to undo all your changes and restore the image to its original state.