You can erase from any area of a pixel layer using the Erase Brush Tool. Erased pixels become transparent. If the brush is used on a vector object or layer, a mask is automatically created and the erasing will be performed non-destructively.
Settings
The following settings can be adjusted from the context toolbar:
Width—the brush (stroke) size in pixels.
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).
Hardness—how hard the edges of the brush are. The brush appears softer as the percentage decreases.
More—tap to display the Brushes dialog to access advanced brush settings.
Force Pressure—Toggle to control brush size with pressure if using a pressure-sensitive device. This overrides brush defaults.
Stabilizer—enables stroke stabilization using either Rope stabilizer or Window stabilizer mode; the former drags the stroke end by a 'rope' to smooth the stroke but lets you introduce sharp corners at increasing rope Length (radius) values by redirecting the slackened rope; the latter will smooth the stroke by averaging sampled input positions within a Window whose size is configurable.
Symmetry—when the Lines setting is set to greater than 0, repeats the brush stroke around a number of axes (defined by the value). The center axis point can be repositioned by dragging it.
Mirror—with symmetry enabled, causes brush strokes to be mirrored along the X and Y axis.
Lines—with symmetry enabled, defines the number of axes around which the brush stroke will be repeated.
Locked—when enabled, prevents the symmetry line from being moved.
Erase Brush Tool