WordPress styles the default audio and video elements, and frankly it’s not an improvement.
Below is the code to turn the audio player from this
into this
function deregister_media_elements(){
wp_deregister_script('wp-mediaelement');
wp_deregister_style('wp-mediaelement');
}
add_action( 'wp_enqueue_scripts' , 'deregister_media_elements' );
Add the code to your theme functions.php file.