WP Multisite: Remove user from all blogs and delete account if removed from one blog

wp-multisite-sitewide-user-remove.php

<?php 
########################################
#
# Sitewide user removal if removed from one blog on WP Multisite
#
# use as MU plugin
#
# Note: this is basic code with no additional security checks
# and error prevention
# and it doesn't reassign user content (it's left "free floating")
#
# USE AT YOUR OWN RISK!!!
#
# UPDATE: Nov 14th 2021 
# * fixed: new accounts couldn't be added to blogs
#
########################################

function sitewide_remove_user_do_delete_site( $user_id, $blog_id ) {
	
	
	switch_to_blog( $blog_id );
	$user = get_userdata( $user_id );
	
    if ( ! $user ) {
        restore_current_blog();
        return new WP_Error( 'user_does_not_exist', __( 'That user does not exist.' ) );
    }
 
    $user->remove_all_caps();
	
	restore_current_blog();	
	
	return true;
}


function sitewide_remove_user( $user_id , $blog_id, $reassign ) {
	global $wpdb;
	
	
	// bail if it's not user list screen (to avoid execution when adding new user)
	if ( ( ! function_exists( 'get_current_screen' ) ) || ( 'users' !== get_current_screen()->base ) ){
		return false;		
	}
	
	
	$user_id = (int) $user_id;
	$user = new WP_User( $user_id );
 
	// bail if user doesn't exist
    if ( ! $user->exists() ) {
        return false;
    }
	
	
	
	// execute only if not super-admin account
	if (! is_super_admin( $user_id ) ) {
	
	
		// get all sites of user
		$sites   = get_blogs_of_user( $user_id );
		foreach ( $sites as $key=>$value) {
			
			// and delete from network skipping current blog
			// as this one is handled by WP core anyway
			if ( $blog_id <> $key ) {
				
				if ( sitewide_remove_user_do_delete_site( $user_id, $key ) ) {
					error_log( 'User '. $user_id . ' removed from blog ' . $blog_id );
				}
				else {
					error_log( 'ERROR: User '. $user_id . ' removed from blog ' . $blog_id );
				}
				
				
			}
		}
		
		
		// delete user account from network
		$meta = $wpdb->get_col( $wpdb->prepare( "SELECT umeta_id FROM $wpdb->usermeta WHERE user_id = %d", $user_id ) );
		foreach ( $meta as $mid ) {
			delete_metadata_by_mid( 'user', $mid );
		}
 
		$wpdb->delete( $wpdb->users, array( 'ID' => $user_id ) );
 
		clean_user_cache( $user );
	
	}
	
}
add_action( 'remove_user_from_blog', 'sitewide_remove_user', 10,32 );