How to Remove Search Text Box in Filter Dropdown

Hi All,

I am working on SQL based KPI in IRIS BI. I want to remove below highlighted search text box in "auto" filter type.

We cannot use other type like only dropdown etc. Is there a way we can do this ? 

One way I can see is writing own control instead of using default control but I am not aware how to do this. I didn't find any sample code for this. 

Is there any sample code available for writing custom control which I can refer.

Please assist