Remove "Posted by Admin" only.

Try these selectors;

.post footer

https://www.w3schools.com/cssref/css_selectors.asp

@fast4u – You would need to make a child theme and copy over the whole leaf_entry_meta() function into the function.php file of the child theme and do your edits to it. You can find the function here on GitHub between line:120 – 156 and the part you will need to edit is between line:141 – 147.

Alternatively you could add

.posted-by {
display: none;
}

to you custom css. Leaves a spare “//” but works well enough for me.

Nothing wrong with the display none solution, but generally (expecially for the theme), it’s better avoid it in favour of code removing directly (in a child theme) to prevent code from being unnecessarily loaded

In addition, edit that function allows you to remove that spare //.