Do you mean:
Sitemap
This is a sitemap over all available pages ordered by namespaces.
If so, this can be changed in inc/lang/<language_code>index.txt. The language code for English is
en[/m], German [m]de[/m], French [m]fr, etc. You may have to purge the cache after each change. You can leave the file empty if you want no headings.