Photoshop is a great software to cut out the background of an image. If you don't have Photoshop, you can download a free trial version.
Cut Out The Background Using The Magic Wand Tool
Here is a short video tutorial on how to easily cut out the background of an image using the Magic Wand tool in Photoshop:
Cut Out The Image Using The Pen Tool
And here is another method using the Pen Tool - this method is much more precise and yields much better results if you are patient and if you make sure to zoom on the image at least 400%:
