This method will generate a notice if you try and remove a sort field that isn't set. This can happen if you call getSortFields, which will return an array like:[0] => 'fieldName asc',[1] => 'fieldName descBut if you try and call:<?php$object->removeSortField('fieldName asc');?>You will get a notice. Instead, you need to truncate the sort order (' asc', ' desc') part of it. Something like:<?php$fieldName = trim(str_replace(array('asc', 'desc')), '', $fieldName);?>