Eraser classic
Remark: do not forget that you can use the History Brush Tool  of Photoshop to restore the opacity of certain parts.

As regards the used algorithm, the plugin proposes two of it:
Sphere Method: means deducting a sphere in the space of colour (r, g, b). The sphere center is the color you wish to erase, and its radius is proportional to the tolerance.
Cube Method: means deducting a cube in the space of colour (r, g, b). The cube center is the color you wish to erase, and its sides are proportional to the tolerance.
For the same tolerance, cube method erases less than sphere method.

Select with the eyedropper the colours you wish from the current application (background colour to erase, foreground colour to protect). Launch the plugin and the greatest part of the work is done

The plugin retrieve automatically the background and foreground colour, from the host application. However, you can modify them from the plugin's dialog, to optimize result. Press Reset to restore the two colours.

The Opacity box re-scales the transparency:
Increase minimum parameter to clean the background.
Decrease maximum parameter to get back certain erased parts.
Auto option allow to adjust automatically minimum and maximum parameters.

The sophisticated algorithm of this plugin, can be useful for subtle replacements of colour. So, in the example below, reflections on the water became red.