Do not show on homepage functions.php code needed

I don’t think your code should work. You have to add_action to some hook (this function takes at least 2 params and you only use one of them).

add_action( $tag, $function_to_add, $priority, $accepted_args );

Also there is no script called float-left-right-advertising registered by this plugin.

Something like this, on the other hand, will work:

function disable_flradv() {
    if ( is_home() || is_front_page() ) {
        remove_action('wp_footer', 'append_code_to_body');
    }
}
add_action('wp', 'disable_flradv');

PS. You also have to be careful, if you want to use is_home (and so on) functions. You shouldn’t use them before wp_query object is initialized.