A commonly used spam protection plugin is Zero Spam which has over 30k active installations. To avoid conflicts when switching from the Zero Spam plugin, it’s recommended to remove any remaining data before installing, activating, and setting up the new spam protection solution. The Zero Spam plugin uses a couple of custom database tables for storage; wp_zerospam_blocked_ips Wp_zerospam_log Suppose the custom database tables from the Zero Spam plugin are not automatically deleted when you uninstall it. In that case, you can use the WP-Optimize plugin or phpMyAdmin to locate them. By using any of them, you can delete the left-over