In case you want to get rid of the background when formatting an image in Keynote, you can use something cool called Instant Alpha. This feature can be found within your Keynote toolbar. If it is not there, you can right-click, go to Customize Toolbar, and find Instant Alpha in the list of features. To remove the background from the image in Keynote, you just click on Instant Alpha and move your mouse cursor over the areas which need to be deleted.