Function to Remove a top level admin menu (taken from WP trac)

functions.php

<?php
/*
    Function taken from http://core.trac.wordpress.org/changeset/15753
    Awaiting release of WP 3.1.0

    Credits: scribu
*/
if ( ! function_exists('remove_menu_page') ) {
    /**
     * Remove a top level admin menu
     *
     * @since 3.1.0
     *
     * @param string $menu_slug The slug of the menu
     * @return array|bool The removed menu on success, False if not found
     */
    function remove_menu_page( $menu_slug ) {
        global $menu;

        foreach ( $menu as $i => $item ) {
            if ( $menu_slug == $item[2] ) {
                unset( $menu[$i] );
                return $item;
            }
        }

        return false;
    }
}