Removing a background in Photoshop is actually surprisingly easy, and is a common task when modifying images. In order to do this, we simply need to access the polygonal lasso tool.
The default tool will usually be the regular lasso tool, but if you hold down the lasso, a few more options will appear. Choose the one that looks like the image above.
In small sections, go over the subject and outline them as close as possible. You can use Ctrl + to zoom in and Ctrl – to zoom out, which will give you more control over the smaller details of the image. When you’re done, go to Select > Modify > Smooth. I usually use 3 pixels. Once you’ve done this, you can use the Eraser tool to get rid of the background. After you’ve removed the entire background, you can fill it with whatever color you choose. I will sometimes use a gradient in order to get a more dynamic look from the background.