With the image open, click on Select (top bar) > Color Range.
From that new window, don’t modify anything.
Just click on the preview image on the color that you want deleted.
Let’s say that you want to delete the green color from that network card.
Click anywhere on the green parts and click “Ok”.
You will notice that the image has a selection now. Hit the “Delete” button from your keyboard. The green color should be removed.