hide or remove all page titles

I would like to hide or remove all page titles in my site. I have linked to a page with the example title shown in dark grey at on the left “Testimonials.” I do not want it to show, nor do I want the other page titles to show. However, if I erase them manually in the dashboard on each page, I’ll have a lot of (no title) pages, and that gets confusing to manage.

I did some research and attempted to use a plugin to remove titles from displaying, but it isn’t actually working. The plugin I tried is called Title Remover by WPGurus.

I also found this article, but I have trouble believing it needs to be this complicated, so I wanted to inquire first. (https://www.theblogstarter.com/how-to-remove-a-page-title-in-wordpress/)

Thank you in advance.

The page I need help with: [log in to see the link]