When a site is upgraded from Joomla 3.1 to 3.2 using FTP or another manual upgrade, a number of extensions show up through the discover install method. When Discovery Install is used for those extensions, AJAX and Content History show up in Components sub-menu.
Create a backup, then delete the "com_ajax" entry in the _menu table (you can search for it in the title column). Afterward, delete the "com_contenthistory" entry in the same table.
You can remove that using phpMyAdmin dropping the row in #__menu that refers to com_ajax.
SQL: DELETE FROM `#__menu` WHERE component_id = (SELECT extension_id FROM `#__extensions` WHERE `name` = 'com_ajax') Replace #_ with your prefix