How to change the colour of specific part of sprite on touch unity?

i am trying to make transparent to a sprite specific part where i touch it.
How can i do it?

 

Hmm, tricky. What defines a "part" of a sprite?

 

@

its like where i click on image,exactly that specific part want to be colour change not anywhere else of its sprite.

 

You still haven't answered the question. What does "specific part" mean to you? The pixel clicked? The arm, if this is a humanoid character? Perhaps your sprite is a checkerboard, and a "part" is one square? Is it the contiguous set of pixels the same color as the pixel clicked?

I give up. If you can't tell us what you're actually trying to do, we can't help you.

 

its an image Alphabet "A" , and i want to make it transparent where i click.