For example,
If I want to remove all the green from this icon without wasting much time how do I do it?:

https://s3.postimg.org/s4n3i24sz/Gaara_Sprite_Thingy.png

If the picture isn't showing then let me know and I will repost it
Thanks in Advance
[Edit] I will be asking for things I need help on later. You have been warned.


P.S. You maybe/maybe not remember my name because in the past I made some posts(very stupid ones)which I highly regret making looking back at it now.