Does app will be removed in installed phones if the app unpublished from AppStore?
No, removing your app from the App Store won't remove it from other people's devices (iPhones/iPads).

Yes, an app that was removed from the App Store but is still installed on a user's device. If the app relies on data from another server (getting data from a database or a news source) an this data cannot be accessed anymore at least parts of the app won'be functional anymore.