Hi Divya,
You can omit the parameter on BrandCode from command object SQL and take care of this at the report-end itself.
1. Create a dynamic parameter on BrandCode and make it 'optional'.
2. To combine the default values and the user's parameter selection, the record selection formula needs to be updated like:
{Table.Field} in ['HN','HQ','HA'] AND (if HasValue({BrandCode}) then {Table.Field}={BrandCode} else True)
Note: Here {Table.Field} is the required column on which the filter will be applied.
Thanks,
Prathamesh