To begin with start with a brand new file in Photoshop, you can do this by selecting File and then New. Upload the image you ...

Open Paint.NET using its desktop ... all those areas are removed and the background is transparent now. Finally, you can save the image as PNG or another format that supports transparent backgroun ...

export the image as a PNG to retain the background transparency. You can now place the image on top of other images without a background or use it for any other purpose. And there you have it!