Remove author in blog post, keeping the date

Hi, I'm managing a page in Norwegian. Could someone please tell me which code to use to introduce the blog posts with "Publisert [date]" rather than "Posted on [date]. I'd also like to remove 'author' as well as 'categories' and 'tags' below. I'm running the site on a child theme for Everest Pro. (It's for www.fian.no) Thanks! -Marit