The Magic Eraser Tool automatically clears continuously colored areas:
In the Toolbox, select the Magic Eraser Tool.
Click on an area to erase.
"Contiguous" checkbox on the Options bar (checked by default) limits the tool's range to adjacent
areas only, while deselicting it allows to erase similar pixels all over image.
In the Options bar, you can also set "Tolerance" (the tool's sesitivity) and stroke "Opacity".
"Anti-alliased" option smooths edges of erased areas.
Tool automatically clears continuously colored areas: