How to edit RSS feed

Hi @rickstar123 you can override archive post template file in your theme and modify it as you want. You can remove title part , remove excerpt and can add any other information regarding to posts. To override single post display you have to override single.php or related file with single-{id}, single-{slug} in your theme.
You can add this PHP code to functions.php in your theme.

function modify_read_more_link() {
    return '';
}
add_filter( 'the_content_more_link', 'modify_read_more_link' );

This will remove all read more buttons in your theme. But if you just want to show complete articles without excerpt this you can achieve by customizing WP Settings. Visit link below.
Image

Thanks Mahammad.

Is this modification to functions.php going to affect my website’s appearance?

I’m only wanting to remove the post title and read more from my RSS feed. I don’t want to modify my sites theme, just how my newsletter appears when I send it out as an RSS feed.