Anyone who has already purchased (even if free) your app will continue to be able to download it forever. If you update the version, they get the new version, not the old one (unless you change the is version require to - then they get the newest one supported by their OS version.
If you pull an app completely (from all markets) you can flag it as being "for legal reasons". this prevents it from being re-downloaded, even from people who already purchased it. But this takes it off all markets, not just some of them.
It sounds like you need to contact Apple directly and describe why you want existing customers to have their right to access your app taken away. Maybe they can make a special case. In general though, they don't allow it.