Remove Divi sidebar styling on BuddyPress / BBPress pages by removing body classes

functions.php

<?php 

add_filter('body_class', 'modify_body_classes', 20);

function modify_body_classes( $classes ) {
  if( is_buddypress() || is_bbpress() ) {
    $remove_classes = array('et_right_sidebar', 'et_left_sidebar', 'et_includes_sidebar');
    foreach( $classes as $key => $value ) {
      if ( in_array( $value, $remove_classes ) ) unset( $classes[$key] );
    }
    $classes[] = 'et_full_width_page';
  }
  return $classes;
}