How to clear the page cache in MediaWiki?
To clear the cache of a page in MediaWiki, add &action=purge to the end of the page’s URL in your browser’s address bar, e.g. :
http://www.yourdomain.com/index.php?title=Main_Page&action=purge
where yourdomain.com is the domain where you’ve installed MediaWiki.
If you are not logged in the wiki, a message will come up asking you to confirm that you want to clear the cache of the page.
More on the MediaWiki cache can be found in their official knowledge base.