I’m not sure where exactly you want to hide the post title, but all the theme files are: Documents ▸ Publii ▸ sites ▸ YOUR_SITE ▸ input ▸ themes ▸ YOUR_THEME
I do not plan to add this option since it will have a bad impact on SEO.
--
Do you appreciate the support you've received today? If so, consider donating to the Publii team by clicking here; we'll be sure to use your donation to make Publii even better!