Remove SELECT A VALUE in cascading parameter in SSRS 2008 R2

Hi,

i have two parameter product group and product name.

For example: if i select 4Wheeler product group,in product name i am getting list of 4 wheeler name (10 Product name), in this case i am getting select a value is included (11 Product name).

Q: How to remove the select a value in the list?

Thanks in advance

Paramesh G