Sometimes you don’t want users to be able to access certain submenu links in the admin. Add the following code to functions.php to make these unavailable.

function remove_submenus() {
global $submenu;
unset($submenu['index.php'][10]); // Removes 'Updates'.
unset($submenu['themes.php'][5]); // Removes 'Themes'.
unset($submenu['options-general.php'][15]); // Removes 'Writing'.
unset($submenu['options-general.php'][25]); // Removes 'Discussion'.
}
add_action('admin_menu', 'remove_submenus');