Trouble with Editing Theme Functions

I tried to add the following code to my theme functions:

add_filter(‘comment_form_default_fields’, ‘unset_url_field’);

function unset_url_field($fields){

if(isset($fields[‘url’]))

unset($fields[‘url’]);

return $fields;

}

Now my website is malfunctioning and I’m getting the error below. I tried to revert to the original code but can’t seem to get it to work. Any suggestions?

Error: add_filter(‘comment_form_default_fields’, ‘unset_url_field’); function unset_url_field($fields){ if(isset($fields[‘url’])) unset($fields[‘url’]); return $fields; }
Warning: Cannot modify header information – headers already sent by (output started at /home3/luxuryr/public_html/wp-content/themes/wp-ellie_basic/functions.php:7) in /home3/luxuryr/public_html/wp-content/plugins/permalink_redirect-2.0.4/ylsy_permalink_redirect.php on line 422