Eraser

You can use the Eraser tool to remove regions of a drawing object. If you create a new zone with the Eraser tool, you can fill this zone with color.

Use one of the following methods to activate this tool:

Select Tools > Drawing Tools > Eraser.
Click the Eraser tool on the Drawing Tools toolbar.

If the Eraser tool is visible in the Drawing Tools toolbar, press [4] to activate it.

Press [Shift]+[4], the default keyboard shortcut.
When using a digital tablet and pen, use the end of the digital pen like you would an eraser on a pencil.