Use Stop VM API to to stop VPS on your server.
HTTP Request
https://hostname:4083/index.php?act=stop&svs=vpsid&do=1
Parameters
| Name | Type | Value | Description | Required | 
|---|---|---|---|---|
| act | GET | stop | The action used to carry out certain operation | Yes | 
| do | GET | 1 | IF set then the particular action will be carried out | Yes | 
| svs | POST | Int | The id of the vps is passed in order to stop the vps | Yes | 
Sample Code
PHP
<?php
    require_once('/usr/local/virtualizor/sdk/enduser.php');
    $key =  '';
    $pass = '';
    $ip = '';
    $admin = new Virtualizor_Enduser_API($ip, $key, $pass); 
    $vid = 3332;
    $output = $admin->stop($vid);
    print_r(json_encode($output));
?>
Curl
curl -k  -L "https://hostname:4083/index.php?
svs=3560&act=stop&api=json
&apikey=your_api_key&apipass=your_api_pass&do=1"
Output
{
    "uid": "321",
    "act": "stop",
    "timezone": 1,
    "timenow": "September 20, 2016, 6:50 am",
    "vpsid": 3560,
    "username": "test@test.com",
    "user_type": "2",
    "preferences": {
        "fname": "test",
        "lname": "test",
        "theme": "default",
        "language": "english",
        "timezone": 1
    },
    "url": "index.php?",
    "rdns": {
        "pdnsid": null
    },
    "support_link": "http://softaculous.com",
    "disable_login_logo": 1,
    "title": "Stop VPS",
    "done": {
        "msg": "The Shutdown signal has been sent to the VPS"
    },
    "status": 0,
    "output": "",
    "time_taken": "0.590"
}