MediaWiki

Sidebar Typing MediaWiki:Sidebar in search bar, and validating with Enter.

Common.css Typing MediaWiki:Common.css in search bar, and validating with Enter.

This hides the [Discussion] tab on pages.

/* CSS placed here will be applied to all skins */
#ca-talk {
    display: none !important;
}

This hides the footer (Vector skin)

/* remove some */

#footer-places-privacy { display: none; }
#footer-places-about { display: none; }
#footer-places-disclaimer { display: none; } 

/* Or remove them all*/
#footer-places { display: none; }

This hides the tools from the sidebar

#p-tb { display: none; }

Mainpage Typing MediaWiki:Mainpage in search bar, and validating with Enter.

Poweredby logo This hides the Poweredby logo on pages.

# Edit LocalSettings.php and add line: 

unset( $wgFooterIcons['poweredby'] );