not possible. The user has already downloaded it in order to show it in their pdf viewer.
This company has some enterprise class software for heavily controlled environments (one where you can place restrictions on what the employees can do with their computer) https://www.locklizard.com/prevent-save/
@shing_shing You have already given the user the document, you can't stop them from downloading it, it could be printed, copied from the temp folder etc.