You’ll get the best results removing solid colors with clear boundaries. To remove areas that are less distinct, select a smaller area and repeat the process.
To remove unwanted elements:
Magic Eraser tool in the Tools palette (or press shortcut E).
As you drag, the selection grows to include the contiguous area that uses similar colors. You can control how much of the image is selected by dragging less or more.
Tool Options
In the Tool Options, you can set the Magic Eraser opacity.