It's my please Allie!
This is actually a customization to have the download option removed from a file. If you would like, I can put you in contact with an account manager who would be able to provide you with a quote.
Unfortunately, this process is a little bit more complex that just removing the "download" button from the preview page as there are several other instances where one file can be downloaded from.
If you would just like the "download" button removed from just the preview page and are okay with it appearing in other areas (such as the folder view, the download folder option, etc.) then we can provide you with the css code without requiring the additional hours.
I know there is already a feature request for this with our development team but we have no timeframe on when and if this can be implemented.