I can not get rid of the add_filter tag in wordpress from the bottom of my page

Question

I am working on a new website on WP and I have this function that appears at the bottom of every page and can't make it invisible:

add_filter('the_title', function($title) { 
  if (is_page()){ 
    $title = ''; 
  } 
    return $title; 
});

how can I get rid of it and not make it appear on every page of the web?

I tried to solve it by making changes in different plugins.