Personalize entry-meta in a no child theme

Good morning guys,

I have a problem with the <header class = "entry-header"> block
if possible I would like to delete this information:

<div class = "entry-meta">
<span class = "byline"> di <span class = "author vcard" itemprop = "author" itemtype = "https://schema.org/Person" itemscope> <a class = "url fn n" href = "xxx "title =" xxx "rel =" author "itemprop =" url "> <span class =" author-name "itemprop =" name "> xxx </span> </a> </span> </span> < / div>

shouldn't create problems on the validation side because then there's Json right?
and also in Json change change the author url with a custom url.
I don't have a child theme, and to make these changes I guess you have to write something in the functons.php child file. If I activate a child theme now, do I lose all customizations?