Magic Eraser Tool

As Simple As Photoshop > Tools > Magic Eraser Tool

The Magic Eraser Tool automatically clears continuously colored areas:

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