Use Erase 
to erase areas of the picture. The pointer changes to the Erase pointer 
. Choose one of the Brush Shapes for the eraser, and set its Size and Angle. See Brush Types.
Note: To remove a large area of the picture, select the area then Delete or Cut the area. Alternatively, use Flood Erase 
.
To use Erase
-
In the Paint Tab
of the Design Panel 
, click Erase 
. -
Choose Paint > Erase.
Erase Part of the Picture
-
Click the Erase icon
. The pointer changes to the eraser pointer
. -
Change the style and width if desired by selecting a Brush Shape, Size and Angle.
-
Drag across the work area to erase an area. Whenever the cursor passes over a pixel that is not transparent, it changes it to transparent.
-
Each time you drag, areas are erased, until another feature is selected. Also use single clicks to erase dots.