need a WP guru

Hello. I need some help!

Please look at this page:
https://www.mgrear.com/news/

I was trying to delete the >> before each of my popular posts listings. I did a search for the character. I found one in a configuration file (I don’t remember which one!), deleted it, saw this error, put the character back, but now I am still getting the error.

The error is:

Warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, ‘feed_links_extra’ was given in D:\home\mgrear.com\wwwroot\news\wp-includes\plugin.php on line 339

Does anyone know how I can fix this?!