Remove title from pages (Delphinus theme)

Hi there,
I can’t seem to remove the titles from each of my pages. I’ve downloaded a plugin called Title Remover which didn’t work when I ticked it to remove the title from some pages. I’ve tried a code, but am not sure I was doing it right? (sorry I’m quite new to WordPress).

I’m using Delphinus theme and there is a big grey bar at the top of each page under my menu which is where it says the title of each page, I’d like to get rid of this big grey bit too.

Thanks