Hi, you have more possibilities, first one is to read manual :)
http://framework.zend.com/manual/en/zend.form.elements.html#zend.form.elements.decorators
second one is to remove decorators you don't need
$t->removeDecorator('Errors');
$t->removeDecorator('HtmlTag');
$t->removeDecorator('Label');
third one (probably the best one for you) is to set only decorators you need.
Following code will set only view helper decorator, so there will be no label, no error message and no html tags
$t->setDecorators(array(
array('ViewHelper'),
));
very good article about decorators is here:
http://devzone.zend.com/article/3450