Removes target menu items from the admin menus.

remove-admin-menus.php

add_action( 'admin_menu', 'remove_breakable_links_from_admin', 9999 );
/**
 * Remove the "breakable" links from the admin menus.  These are the links deemed to break the site unless you know
 * what you're doing.
 *
 * @since 1.0.0
 *
 * @return void
 */
function remove_breakable_links_from_admin() {
	global $submenu;

	// Loop through the configuration of items to be removed.
	foreach ( _get_config_admin_submenu_items_to_remove() as $page => $to_remove ) {

		// Nope, this submenu page doesn't exist for this user. Let's skip it.
		if ( ! isset( $submenu[ $page ] ) ) {
			continue;
		}

		// Remove this page's menu items.
		_remove_submenu_items_from_admin_page( $page, $to_remove );
	}
}

/**
 * Get the configuration for the admin submenu items to be removed.
 *
 * @since 1.0.0
 *
 * @return array
 */
function _get_config_admin_submenu_items_to_remove() {
	return array(
		/*=============================================================
		 * Format is:
		 *
		 * page => array of items to be removed
		 *
		 * Typically, you use the submenu slug for a specific item to remove.
		 * Why not the menu name?  Internationalization.  The name will change,
		 * but the slug stays the same.
		 *
		 * For certain menu items, such as the Settings menu, the slug is not
		 * available in the $submenu global. Darn. So instead, we use the link.
		 *============================================================*/
		// On the themes.php admin page, use the submenu slug.
		'themes.php'          => array( 'customize', 'edit_themes' ),
		// On the Settings page, use the PHP link as the slug is not given in $submenu.
		'options-general.php' => array( 'options-discussions.php', 'options-permalink.php' ),
	);
}

/**
 * Remove the given menu items from the given submenu page.
 *
 * @since  1.0.0
 * @ignore
 * @access private
 *
 * @param string $page                 The given submenu page.
 * @param array  $menu_items_to_remove Menu items to remove.
 *
 * @return void
 */
function _remove_submenu_items_from_admin_page( $page, array $menu_items_to_remove ) {
	global $submenu;

	foreach ( $submenu[ $page ] as $index => $menu_item ) {

		// Loop through the items to be removed.
		foreach ( $menu_items_to_remove as $to_remove_item ) {

			// Nope, the item to be removed isn't in this menu item. Let's skip it.
			if ( ! in_array( $to_remove_item, $menu_item, true ) ) {
				continue;
			}

			// Remove this menu item.
			unset( $submenu[ $page ][ $index ] );
			break;
		}
	}
}