Documentation says that in order to use outputPanel as a place holder for un-rendered components the layout="none" attrribute should be used. This works only from rendered="false" to rendered="true" but not the other way, so once a component is rendered there is no way to un-render it with ajax request.
The RichFaces demo explains how to use the layout="none" attribute but then shows a completely different way to use the outputPanel... WITHOUT the layout="none" attribute.