Example of custom action to delete cct item in jet form builder. Hook name is `delete-cct`.

functions.php

<?php
function jetFormBuilder_deleteCCT( $request, $action_handler ) {
	$cct = \Jet_Engine\Modules\Custom_Content_Types\Module::instance()->manager->get_content_types( 'my_custom_cct' );
	if($cct){
		$handler = $cct->get_item_handler();
		$item = $cct->db->get_item( $request['cct_item_id'] );
		/*
		 * Update CCT
		 * $handler->update_item([
		 * 		'_ID'            => $request['cct_item_id'],
		 * 		'some_cct_field' => $request['cct_update_field']
		 * ]);
		 */
		if($item)
			$handler->delete_item( $request['cct_item_id'], false );
	}
}
add_action( 'jet-form-builder/custom-action/delete-cct', 'jetFormBuilder_delteCCT', 10, 2 );