@robert didn't work 

🙁

@qurnaz,

Ok, the code is updated. Please remove the old one from your website and use this one:

function remove_wpforo_about_fields( $fields ){
    $remove_fields = array('about');
    if( !empty($fields) ){
        foreach( $fields as $r => $rows ){
            foreach( $rows as $c => $cols ){
                foreach( $cols as $f => $field ){
                    if( $field && in_array($field, $remove_fields) ){
                        unset($fields[$r][$c][$f]);
                    }
                }
            }
        }
    }
    return $fields;
}
add_filter( 'wpforo_get_account_fields', 'remove_wpforo_about_fields');

if it doesn't work, please show mere how are you adding the code and where you check it.