How Do I Know If My Website Is Hidden With Hide My WP Ghost?

Make sure you follow the setup instructions:
https://hidemywpghost.com/hide-my-wp-how-to-install-the-plugin/

You can then use external WordPress detectors to verify if you are 100% hidden:

wordpress vulnerability detector

http://whatwpthemeisthat.com/
http://www.wpthemedetector.com/
https://whatcms.org/
https://wpplugins.tips/wordpress-vulnerability-detector/

If the WordPress Detectors still find your website please contact usĀ and we will check if there are some theme incompatibilities.