Deletes users with customer role in WooCommerce that do not have orders.

delete-customers-without-orders.php

<?php
/**
 * Deletes customers without orders
 *
 * To run the script:
 * wp eval-file delete-customers-without-orders.php
 */

// Query for customers registered since this date.
$date_after = '2000-01-01';

// Don't delete accounts that have been created in the last 30 days.
$timeframe   = strtotime( '-30 seconds', time() );
$date_before = date( 'Y-m-d', $timeframe );

WP_CLI::log( "Finding all users registered between {$date_after} and {$date_before}." );
WP_CLI::log( ' ' );

$customer_ids = find_customer_ids_registered( $date_after, $date_before );

WP_CLI::success( 'Found ' . count( $customer_ids ) . ' customer accounts to verify.' );
WP_CLI::log( '' );

foreach ( $customer_ids as $customer_id ) {
	$user = get_user_by( 'id', $customer_id );

	$role_eligble_for_deletion = user_role_eligible_for_delete( $user );
	if ( ! $role_eligble_for_deletion ) {
		WP_CLI::log( "Customer ID: {$customer_id} has a role that is not eligible for deletion." );
		continue;
	}

	$user_has_posts = customer_has_posts( $customer_id );
	if ( $user_has_posts ) {
		WP_CLI::log( "Customer ID: {$customer_id} has posts." );
		continue;
	}

	$user_has_order_postmeta = user_has_order_postmeta( $customer_id );
	if ( $user_has_order_postmeta ) {
		WP_CLI::log( "Customer ID: {$customer_id} has order postmeta." );
		continue;
	}

	if ( wpcli_is_hpos_enabled() ) {
		$user_has_order_meta = user_has_orders_meta( $customer_id );
		if ( $user_has_order_meta ) {
			WP_CLI::log( "Customer ID: {$customer_id} has order meta." );
			continue;
		}
	}

	// Any other checks you need to do?
	// Need to check for reviews or comments?

	WP_CLI::log( "Deleting customer: {$customer_id}" );
	delete_customer( $customer_id );
	WP_CLI::success( "Customer deleted: {$customer_id}" );
}

/**
 * Return Customer IDs registered before a date and from a date.
 *
 * @param string $date_after  Find after this date (including the date).
 * @param string $date_before Find before this date (including the date).
 *
 * @return array|object|\stdClass[]|null
 */
function find_customer_ids_registered( string $date_after = '', string $date_before = '' ) {
	global $wpdb;

	$query = "SELECT DISTINCT users.ID FROM {$wpdb->users} users
    WHERE users.user_registered <= %s
    ";

	$datetime    = strtotime( $date_before );
	$date_before = date( 'Y-m-d 23:59:59', $datetime );

	$prepared_arguments = [ $date_before ];

	if ( $date_after ) {
		$datetime_after = strtotime( $date_after );
		$date_after     = date( 'Y-m-d 23:59:59', $datetime_after );

		$query               .= ' AND users.user_registered >= %s';
		$prepared_arguments[] = $date_after;
	}

	$query = $wpdb->prepare(
		$query,
		$prepared_arguments
	);

	return $wpdb->get_col( $query );
}

/**
 * Check if customer has a role.
 *
 * @param object $user
 * @return bool
 */
function user_role_eligible_for_delete( $user ) {
	$can_delete = true;

	// Customer does not have any roles set, so we can delete.
	if ( ! $user->roles ) {
		return true;
	}

	// This covers the case where customer may have multiple roles.
	// If any of the roles is not subscriber or customer, we cannot delete.
	foreach ( $user->roles as $role ) {
		if ( ! in_array( $role, [ 'subscriber', 'customer' ], true ) ) {
			$can_delete = false;
		}
	}

	return $can_delete;
}

/**
 * Check if user has posts.
 *
 * @return bool
 */
function customer_has_posts( $user_id ) {
	global $wpdb;
	$posts = $wpdb->get_col( "SELECT ID FROM {$wpdb->posts} WHERE post_author = $user_id LIMIT 1" );
	if ( $posts ) {
		return true;
	}

	return false;
}

/**
 * User has a postmeta key assigned for _customer_user.
 *
 * @param int $user_id
 * @return bool
 */
function user_has_order_postmeta( $user_id ) {
	global $wpdb;
	$meta = $wpdb->get_col( "SELECT ID FROM {$wpdb->postmeta} WHERE meta_key = '_customer_user' AND meta_value = $user_id LIMIT 1" );
	if ( $meta ) {
		return true;
	}

	return false;
}

/**
 * User has a ordermeta key assigned for _customer_user.
 *
 * @param int $user_id
 * @return bool
 */
function user_has_orders_meta( $user_id ) {
	global $wpdb;
	$meta = $wpdb->get_col( "SELECT ID FROM {$wpdb->orders_meta} WHERE meta_key = '_customer_user' AND meta_value = $user_id LIMIT 1" );
	if ( $meta ) {
		return true;
	}

	return false;
}

/**
 * Checks if HPOS is enabled.
 *
 * @return bool
 */
function wpcli_is_hpos_enabled() {
	return class_exists( OrderUtil::class ) && OrderUtil::custom_orders_table_usage_is_enabled();
}

/**
 * Does a direct SQL query to delete the customer.
 * This is much faster than wp_delete_user().
 *
 * @param integer $customer_id Customer ID.
 */
function delete_customer( $customer_id ) {
	global $wpdb;
	$wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}usermeta WHERE user_id = %d", $customer_id ) );
	$wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}users WHERE ID = %d", $customer_id ) );
}