Theme(Responsive) remove posted by date

Hi,

I’m quite new to WordPress and I’m still trying to figure out a lot of stuff on my own. However, I’ve found a challenge that I can’t overcome. I’ve found some documentation but I can’t solve the problem.

I want to remove ‘posted by and date’ on every page and post.
The link to my website is https://christian-ravn.dk/wordpress/ and I use the ‘Responsive theme’. I hope you can help a rookie.

Thanks in advance ??