How to remove the Theme Customization Button from the dashboard and themes options page?

With the lastest version of WordPress (4.3) you can now natively remove the customizer’s theme switch setting without resorting to CSS hacks.

/**
 * Remove customizer options.
 *
 * @since 1.0.0
 * @param object $wp_customize
 */
function ja_remove_customizer_options( $wp_customize ) {
   //$wp_customize->remove_section( 'static_front_page' );
   //$wp_customize->remove_section( 'title_tagline'     );
   //$wp_customize->remove_section( 'nav'               );
   $wp_customize->remove_section( 'themes'              );
}
add_action( 'customize_register', 'ja_remove_customizer_options', 30 );