You are almost there, just find the PHP file, which starts with content-
, edit it, and remove the the_title()
function.
Why? Well, because this line of code get_template_part( 'content', 'page' );
seeks for a PHP file in your theme's folder, which starts with content-
.
EDIT: The function will do a PHP require()
for the first file that exists among these, in this priority:
wp-content/themes/your_theme/loop-index.php
wp-content/themes/your_themechild/loop-index.php
wp-content/themes/your_theme/loop.php
wp-content/themes/your_themechild/loop.php
So check those files too.