Isolating and altering a specific color within an image

I would say the easiest way to do this is with, believe it or not, the magic wand tool. If you set the tolerance to a very low value between 0 and 5, contiguous off, then click on the pink it will select a very narrow range of pink shades. Now create a blank layer and switch to that layer so the selection applies there. With the foreground color set to white press alt or option backspace/delete to fill the selection with white. Now go back and repeat with the pink shades not selected and again fill the empty layer with white. You will have to do this four or five times to remove all the non cyan colors. It took me about 5 minutes to get the below

Another possibility might be using a Hue/Saturation Adjustment Layer with »Magentas« as the target and, if necessary, manually adjusting the range.

Edit:

As JJMack​ told you, You can use the color range command from Select Menu above.
Select> color range  and when the dialog box is open go outside and click on the color you need to select.
Use the fuzziness to adjust the range of color and press Ok.

Now you have select the color you need to select then you can delete it.

Try playing with select color range.  See if that is useful for what you want to do