add_filter( 'wcfm_product_simple_fields_tax', function( $fields, $product_id ) {
    if( wcfm_is_vendor() && isset( $fields['tax_class'] ) && isset( $fields['tax_class']['options'] ) ) {
        if( is_array( $fields['tax_class']['options'] ) && isset( $fields['tax_class']['options']['digital-goods'] ) ) {
            unset( $fields['tax_class']['options']['digital-goods'] );
        }
    }
    return $fields;
}, 999, 2 );