what's going on here is that both rpm and yum commands act on rpm's database of packages that are installed: they don't act on a file. otherwise, you couldn't delete a .rpm file after you'd installed it: you'd have to keep every .rpm file you'd ever installed around somewhere in order to be able to remove them. which would be a bit silly.
so you can't do an rpm removal operation on a file, exactly. that's just...not how the system works. you're removing something that's listed in rpm's database of installed files; which is a package name, not a filename with a .rpm extension.
i'd expect 'yum remove z600cups', 'rpm -e z600cups', 'yum remove z600cups-1.0-1.i386', 'rpm -e z600cups-1.0-1.i386' would all work. but not the commands you tried.