Question

The simplest way to permanently get rid of unwanted file

Answer 1

Using an eraser. Plenty of utility programs like Glary offer a permanent deletion.

I personally use a program called eraser.

Answer 2

follow steps in url :
http://www.wikihow.com/Clear-up-Unnecessary-Files-on-Your-PC

Answer 3

@karimse07 That may not be permanent. It can still be pretty easily recovered without something that does safe data erasure.