editing the MediaWiki navigation pane
From Sharkysoft Wiki
After setting up a Mediawiki wiki, you may wish to edit the navigation pane (called the sidebar) that appears on the left side of the page (if you are using the Monobook skin).
If you have sufficient privileges, you can edit the navigation sidebar just like any other wiki page. The page is called "MediaWiki:Sidebar".
The default contents of this page are:
* navigation ** mainpage|mainpage ** portal-url|portal ** currentevents-url|currentevents ** recentchanges-url|recentchanges ** randompage-url|randompage ** helppage|help ** sitesupport-url|sitesupport
Simply remove the lines associated with the links you don't want to see.
Good luck!