Removing date and author doesnt work

Clear the cache and reload. Check if it works.

Already did that, but didnt work.

.vcard{
display:none!important;
}

copy paste this code.

Did that, cleared cache and opened the website in another browser that was never on that page. Still the author and date is displayed.

Fixed it by adding this code in the additional css via the customizer. Unfortunately adding this code in your plug-in didnt work.