To Install and remove a Toolbar bar in Mozilla is some what different from Internet explorer. To remove a toolbar in Mozilla Firefox Click Tools in menu bar (above) & then click Add-ons .
A new window will open Go to Extensions .Now select the toolbar you want to remove from your Firefox. Similarly you can uninstall themes .Go to second session Themes . Add or remove your favourite themes in Firefox. For time being their are limited number of themes for latest versions of Firefox mozilla.
. You browse for Firefox themes at http://en-US.add-ons.mozilla.com/en-US/firefox/22.214.171.124/themes/