Thread:Project:Support desk/Sperren von SpecialPages/reply

What did you try until now?

Instead of hacking the MediaWiki files, if there was a hook, you should use it.

Apart from that I don't think that modifying SpecialPage.php alone would help you much to hide user names: Information about user names are present at many different places throughout MediaWiki: In the page history, in the recent changes, in the new users log... They can also be called via the API... Restricting access to SpecialPages.php won't help; if you want to see user names, you can easily get them from somewhere else.