Yes, you have to edit the php file, but you must also edit it again when you update the theme to next version,
In theme-functions.php which is under “incudes” folder. Find the first function:
/*Post meta info*/
if( !function_exists( 'van_posted_on') ){
function van_posted_on(){
?>
<span class="blog-article-info"><a href="<?php echo get_author_posts_url( get_the_author_meta( 'ID' ) );?>"><?php printf(__('By %s','OldCar'),get_the_author());?></a> / <?php printf( __( 'in %2$s', 'OldCar' ), 'entry-utility-prep entry-utility-prep-cat-links', get_the_category_list( ', ' ) ); ?> / <?php the_time(get_option('date_format'));?></span>
<?php
}
}
Replace it to:
/*Post meta info*/
if( !function_exists( 'van_posted_on') ){
function van_posted_on(){
?>
<span class="blog-article-info"><a href="<?php echo get_author_posts_url( get_the_author_meta( 'ID' ) );?>"><?php printf(__('By %s','OldCar'),get_the_author());?></a> / <?php the_time(get_option('date_format'));?></span>
<?php
}
}