There is a easy way to delete the file located at FTP server using CFNetwok framework.
After access the server, run the following code.
SInt32 errorCode; Boolean success = CFURLDestroyResource(url, &errorCode);
CFURLDestroyResource is defined by CFURLAccess.h
Good luck.
ashphy coding 
This doesn’t work with directories, you will get kCFURLUnknownSchemeError which means that it doesn’t understand the scheme (ftp). Only works with HTTP.