I have a Project which is running on client side.i have to develop a program to delete some useless files from the project which is running on client side.so what we have to do? Should we go for exe,dll,batch,patch or ocx
i am confused how it will work how it update my old project?

Are you using an installer?

With most installers, you can run scripts after installation, so you could simply have an installer that upgrades the existing product and, as part of the process, removes unused files as well.

That will probably give the best user experience if you ask me.