delete_user_meta_data()

function delete_user_meta_data() {
	global $wpdb;
	$customer_id_meta_key = $wpdb->get_blog_prefix() . Customer::CUSTOMER_ID_META;

	// all meta-keys => value to be deleted
	$meta_keys = [
		$customer_id_meta_key                => '',
		Nav_Items_Meta_Box::USER_INITIALIZED => '',
		User_Profile_Settings::SYNC_PASSWORD => '',
	];

	// Delete metadata
	foreach ( $meta_keys as $key => $value ) {
		\delete_metadata( 'user', null, $key, $value, true );
	}
}