Hi Shiva,
Please check if below solution helps.
#1 - Remove the field group annotations for the field which you don't want to show up in the adapt filter list (this will push the field to default grouping, not to basic)
#2 - You need to set the odata filterable property of field as false; as of now the cds annotations are not seting this property, so you can do this using ABAP in the define() of the MPC_EXT class. Below is sample code for it.
model->get_entity_type( '<your entity name>' )->get_property( '<your desired property>' )->set_filterable( abap_false ).