iOS Please Help Me in this XCode Programming

please calling it "programming in xcode" or "programming xcode".
XCode is just the IDE to develop in..
First of all, your still thinking of Windows applications or such, we just don't terminate an app if something fails, we just think of another way.. Just killing your app when something goes wrong will irritate the user..

Now for your question, it's basically a simple use of NSFileManager.
you can detect there if something exists at a special path, and if it founds it, you can delete it with the same filemanager.. Did you even try coding this yet?

I don't believe that /var is inside the app sandbox. This is therefore intended to be an app that runs on a jailbroken device, I guess. It's a strange idea for an app.

adildsw - You are probably going to have to learn how to program using Objective C for your apps. People here help other people with problems and help people learn, but almost never do the work for you. Your question comes up from time to time but I have never seen anyone so far do the work for you.

Plus if someone answers this question then you will be back with another question as you try to tackle another problem you don't understand how to solve.

My advice. If you want to program, learn how to program.

I started with this book "Learn C on the Mac" it's a good place to start learning about programing. Or 2.... Hire a person to write the app for you.