Hide submenu wordpress?

If you deal with wp menus you shoudl use admin_menu filter.

add_filter('admin_menu', 'admin_menu_filter',500);
function admin_menu_filter(){
    remove_submenu_page( 'themes.php', 'widgets.php' );//widget
    remove_submenu_page( 'themes.php', 'theme-editor.php'); //editor
    remove_submenu_page( 'themes.php', 'theme_options' ); //theme-option
}
add_action('admin_print_styles-themes.php', 'hide_customize');
function hide_customize(){
    echo '<style>#customize-current-theme-link{display:none;}</style>';
}

you can place it to your plugin or functions.php in your theme.