How can I force user logout from a JavaScript library in a custom module?

I've written a custom module for Drupal 8 to monitor user device location frequently. If a user goes out of an allowed zone boundary, I need to force logging the user out of the website. I created following files in the module folder (gps_test):

1. File gps_test.info.yml
2. File gps.js: JavaScript program to monitor the user device's GPS location.
3. File gps_test.libraries.yml: Contains the gps.js library.
4. File gps_test.module: Implements a hook to attach the JavaScript library on every page load.

function gps_test_page_attachments(array &$page) {
  $page['#attached']['library'][] = 'gps_test/gps';
}

How can I force the user being logged out (or prevent the user from using the website) from the gps.js library?

As @Tushar mentioned it, you can use the user_logout() function.

Simplest way I see is to log your user out with an AJAX call when your JS detects that the user needs to be logged out. Here is a basic example of how it can be done.

In your JS, you need to add:

Drupal.behaviors.logout= {
  attach: function(context, settings) {
    if(yourConditionToLogOutUserisMet) {
      $.ajax({
        url: "/log-me-out", // custom route to log current user out
        success: function(data) {
          // do whatever you want on success of your ajax call
        }
      });
    }
  }
}

Then, create your custom route in gps_test.routing.yml

gps_test.my_custom_log_out:
  path: '/log-me-out'
  defaults:
    _controller: '\Drupal\gps_test\Controller\MyLogOutController::logUserOut'
  requirements:
    _permission: 'access content'

And finally, create the route controller:

namespace Drupal\gps_test\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\HttpFoundation\JsonResponse;


class MyLogOutController extends ControllerBase {
  function logUserOut() {
    if ($this->currentUser()->isAuthenticated()) {
      user_logout();

      return new JsonResponse([
        'message' => "Current user session has ended.",
      ], 200);
    }
  }  
}