How to restrict Category List (drop down values) in Activity Search

Hello All,

Scenario:CRM 2007

Activity Search >> Search Criteria >> Category

The drop down menu shows the values defined in IMG assigned to all the transaction types(standard plus custom). But I want to see only the ones associated with the custom or Z transaction types.Is there an option to hide the standard categories which are not required as a search criteria.

Regards

Varun