1.Background Erase Tool(E)
The background eraser tool lets you erase pixels on a layer to transparency as you drag, this allows you to erase the background while maintaining the edges of an object in the foreground. By specifying different sampling and tolerance options.
2.Magic Eraser Tool(E)
When you click in a layer with the magic eraser toll, the tool automatically changes all similar pixels. If you're working in the background, or in a layer with locked transparency, the pixels change to the background color, otherwise, the pixels are erased to transparency. You can choose to erase contiguous pixels only or all similar pixels on the current layer.