The Smart Erase tool erases similarly colored areas of an image, which is very useful for removing solid color backgrounds.
Do one of the following:
In the Tool Options pane, customize the Smart Erase tool:
Opacity: Drag the Opacity slider to adjust the transparency of the Smart Erase tool.
Sample All Layers: Select Sample All Layers to make the Smart Erase tool take into account the contents of every layer in your image, not just the selected layer.
Smooth Edges: Select Smooth Edges to naturally smooth the outline of the Smart Erase tool. With Smooth Edges unselected, the outline will be a little more precise but jagged.
Drag on the canvas to erase. The more you drag, the more the Smart Erase tool will erase. If you’d like to erase the entire layer, drag until the Tolerance value reaches 100%.