You can use an IIS Native-Code module to remove any headers in IIS 7.5 (in fact, the same module should work for IIS 7.0 - 8.5).
Native-Code modules differ from the more common Managed modules, as they are written using the win32 APIs rather than ASP.NET. They work for all requests, including static pages and images.
Binaries and source code of an example Native-Code module for removing headers in IIS 7.0 to 8.5 are available in the following article. This module is a simple MSI install and will remove the "Server" "X-Powered-By" and "AspNet Version" headers by default. Other headers can be removed using the IIS configuration.
http://www.dionach.com/blog/easily-remove-unwanted-http-headers-in-iis-70-to-85