You can erase from any area of your image, including any vector objects, using the Erase Brush Tool. Erased pixels become transparent.
Settings
The following settings can be adjusted from the context toolbar:
Width—the brush (stroke) size in pixels. Type directly in the text box or drag the pop-up slider to set the value.
Opacity—how see through the brush is. 100% opacity erases pixels completely on the first pass. A lower opacity only partially erases the pixels.
Flow—how fast the brush effect is applied (1% is very slow, 100% is immediate). Type directly in the text box or drag the pop-up slider to set the value.
Hardness—how hard the edges of the brush are. The brush appears softer as the percentage decreases. Type directly in the text box or drag the pop-up slider to set the value.
More—click to display the Brushes dialog to access advanced brush settings.
Force pressure to control size—Click to control brush size with pressure if using a pressure-sensitive device. This overrides brush defaults.
To use the Erase Brush tool:
Use the Layers panel to select the layer that you want to erase from.
Click the Erase Brush tool.
The tool uses a soft-round brush by default. To use a different brush style, choose one from the Brush panel.
On the context toolbar, change the brush values as desired.
Drag within the image to erase pixels beneath the brush cursor.