PowerPoint has come a LONG way in terms of editing images. Some of the tools it provides are simply fantastic, like the background removal tool for images. You can remove the background from an image, provided you find a suitable image, with ease! Check out this video I made showing how to remove the background from an image.
It does help, though, to choose an image with a suitable background. Images with lots of colour and detail are difficult. Rather do a search for images with single colour backgrounds or go for images with the backgrounds already removed (this will save you some time!).