Hi there,
you will need to remove them from your posts also.
So open single.php and entry-content.php, content-entry-widget.php and remove
<time class="entry-date" itemprop="datePublished" datetime="<?php echo esc_attr( get_the_date( 'c' ) ); ?>"><?php echo esc_html( get_the_date() ); ?></time>
from inside.
Try installing the WP Editor plugin to enhance the default editor and then navigate to the /themes/olsenlight/ folder to find the file.
If you decide to proceed with this modification I would suggest you create a child theme, copy over the files you are editing and make the modifications there. This will allow your changes to survive future theme updates. If you directly edit the theme’s files, all changes will be lost once you update.
Have a look at this guide to learn more about child themes and how to create one
https://www.cssigniter.com/ignite/beginners-guide-child-themes/