Which part of this code can i remove

Hi

Warning: Cannot modify header information – headers already sent by (output started at httpdocs/cheap-holidays/wp-content/plugins/seo-title-tag/seo-title-tag.php:3501) in /httpdocs/cheap-holidays/wp-includes/feed-rss2.php on line 2

Around line 3501 we have this
}

// returns class=current if the strings exist and match else nothing.

// Used down on the top nav to select which page is selected.

function is_current($aRequestVar,$aType) {

Should i delete all of this?

Kevin