Just to clarify Michael... there are two ways to hide unwanted parent members...
You can however hide unwanted levels. If you already know that you will only view data from a specific level then in the left hand "Data Panel" expand the hierarchy to see the different levels and just drag the required level to the crosstab.
The other option is to right click on the hierarchy header in the crosstab and choose the option "Show Level". This will allow you to choose which levels to show and which to hide.
Regards
Ian