This Wiki article will explain how to hide Internet Information Services (IIS) version in Response Header.
This can be tested by using Fiddler
Download and install UrlScan 3.1 security tool from http://www.iis.net/downloads/microsoft/urlscan.
If IIS version 7 is used then add additional role 'IIS6Metabase Compatability' is required. IIS > IIS6 Management Compatability>IIS6Metabase Compatability.
After installing UrlScan tool navigate to C:\Windows\System32\inetsrv\urlscan and open UrlScan.ini with text editor. Set 1 for RemoveServerHeader option (as in screenshot below) save and then close the file.
You must restart the server for changes to take effect