I create many virtual server on my server but when create new users they can access my virtual server via “File Manager”.
If i disable “File Server” module they could not access their virtual servers.
Why are you creating Webmin users directly in a Virtualmin system? Generally, you’d be doing that because you wanted them to have more privileges. The point of Webmin is administrative (root-like) access for one or more services. It doesn’t sound like that’s what you want, and so I’m wondering why you aren’t creating these users in Virtualmin instead (where they would be limited in their access, by default)?
If you really do have a reason for them to Webmin users, and they need elevated privileges for something, but not the File Manager, you can edit their ACL in the File Manager. Click on File Manager in that page. That will allow you to configure some access control limits. One of the options is Allow access to directories and another is Access files as Unix user. Both of these are locked down by default for Virtualmin users…but Webmin is an administrative tool.