This is not currently possible within a single Lansweeper installation with a single database. Asset access is, for now, "all or nothing". A user can either see all assets or no assets. The ability to restrict access to specific assets has been requested by several customers and is on our customer wish list, but we do not have an estimated release date for this feature yet.
Restricting access to specific assets will require a thorough re-evaluation of our code. We would not only need to restrict what people can access on web console pages, but what they can see within the report builder as well.