Remove Author Box For Selected CPT

function.php

function remove_author_box( $post_id ) {
    // - Update the array for selected CPT, where you do not want to display the author box
    $CPT = array('a'=>'Woocommerce', 'b'=>'WP Deals Engine');
    // If this isn't a selected CPT post, don't update it.
    if ( in_array ($_POST['post_type'], $CPT )) {
        // - Update the post's metadata.
        update_post_meta( $post_id, 'author_disp', 'NO');
    }
}
add_action( 'save_post', 'remove_author_box');

Thanks for replying but the code simply does not work.
Any other ideas?

I am using:

function remove_author_box( $post_id ) {
// - Update the array for selected CPT, where you do not want to display the author box
$CPT = array('a'=>'product');
// If this isn't a selected CPT post, don't update it.
if ( in_array ($_POST['post_type'], $CPT )) {
// - Update the post's metadata.
update_post_meta( $post_id, 'author_disp', 'No');
}
}
add_action( 'save_post', 'remove_author_box');