This API is used to Delete Note
Please check example usage of Vision Helpdesk API

Operation : delete_node
Module : ticket

$postfields["vis_module"] = "ticket";
// This is the module under which you wish to perform operation

$postfields["vis_operation"] = "delete_node";
// This is the operation field

$postfields["vis_remark_id"] = 1;
// Note id that you wish to delete

Below is API URL example to Delete Note

http://visiononlinedemo.com/support/api/index.php?
&vis_txtusername=admin
&vis_txtuserpass=21232f297a57a5a743894a0e4a801fc3
&vis_module=ticket
&vis_operation=delete_note
&vis_remark_id=75

OR use "access token" to Delete Note

http://visiononlinedemo.com/support/api/index.php?
&vis_txttoken=T0RSbU56TmpZemxoTlRabU1XWTJOV1ZtT0RWa1ltUm1NR1F6WldJell6VT0=
&vis_module=ticket
&vis_operation=delete_note
&vis_remark_id=75