Mediawiki

You can download the php file VectorTemplate.php from the folder /skins/Vector. Then comment out lines 270,271,272 and also lines 285,286,287 then you can re-upload the file to its original location. Remember always make a backup of the original file just incase. Also my assumption is that when you upgrade your wiki, the changes made to this file may be reverted. To then remove the text Tools on the Side bar, in your wiki, navigate to MediaWiki:Sidebar, when there, remove the text written Tools, that should remove it totally. Take note that when logged in, even as a bureaucrat, you wont be able to see the tools section, so its best you keep important links elsewhere so that you can reach the pages still.

Sidebar width in Vector skin (CSS)

You can change the width of your sidebar by adding the following CSS rules to your MediaWiki:Vector.css. The standard width in vector skin is 10em. The following example changes the width to 12em:

/* increase Vector sidebar width */
div#mw-panel { width: 12em; }
div#footer, #mw-head-base, div#content { margin-left: 12em; }
#left-navigation { margin-left: 12em; }

Mediawiki:Common.css

#ca-edit {
  display: none !important; 
}
#ca-history {
 display: none !important;
}

#pt-createaccount {
 display: none !important;
}

#pt-login {
 display: none !important;
}