With GeneratePress Theme, you can easily disable Post & Page Title, following these steps:
Step 1. Edit Post (or Page) you want to disable Title
Step 2. Scroll down and click on Disable Elements > Check on Content Title > Publish
I use WordPress 5.0 so the Post is slightly different from the previous version of WordPress.
If you don’t see Layout Section. Just click on “three dots” > Options
Then check on Layout
WordPress will automatically reload the page and save the settings!