function custom_wpf_remove_tags( $update_data, $user_id, $contact_id, $form_id ) {

    if ( $form_id == 1 ) {

        wp_fusion()->crm->remove_tags( array( 'Tag Name One', 'Tag Name Two' ), $contact_id );

    }

}

add_action( 'wpf_forms_post_submission', 'custom_wpf_remove_tags', 10, 4 );