Remove the website / URL field in WordPress comment form.

/**
 * Remove webiste field from WordPress comment form
 * 
 * Removes the website field when comments form is displayed with comment_form()
 * 
 * @since 1.0
 */
function velocity_remove_comment_form_website_field( $fields ) {
  
  if ( isset( $fields['url'] ) ) {
    unset( $fields['url'] );
  }
  
  return $fields;
}
add_filter( 'comment_form_default_fields', 'velocity_remove_comment_form_website_field' );

Also refer: Remove Comment Author Link In WordPress Comment List