By action hook you can simply remove any input fields exist.

remove_action('WooShopFilter_fields','WooShopFilter_field_keyword',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_categories',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_tags',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_price_range',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_order',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_orderby',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_onsale',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_in_stock',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_keyword',30);
remove_action('WooShopFilter_fields','WooShopFilter_field_sku',30);