Answered Create, update and delete doc via API

<?php
// first, define what we want to create:
  $parent       = 42;
  $pagetitle    = 'Example Page';
  $longtitle    = 'Example - A New Document Created Through The Modx API';
  $alias        = 'example-page';
  $description  = 'Example description...';
  $template     = 5;
  $published    = 1;
  $content      = '<p>This is some sample content.</p>';
  $tv_img       = 'example.jpg';
  
// secondly, create the new resource and save it:
  $doc = $modx->newObject('modDocument');
  $doc->set('parent',$parent);
  $doc->set('pagetitle',$pagetitle);
  $doc->set('longtitle',$longtitle);
  $doc->set('alias',$alias);
  $doc->set('description',$description);
  $doc->set('template',$template);
  $doc->set('published',$published);
  $doc->setContent($content);
  
  $doc->save();

$fields = array(
  'parent'       => 42,
  'pagetitle'    => 'Example Page',
  'longtitle'    => 'Example - A New Document Created Through The Modx API',
  'alias'        => 'example-page',
  'description'  => 'Example description...',
  'template'     => 5,
  'published'    => 1,
  'content'      => '<p>This is some sample content.</p>',
);

$modx->runProcessor('resource/create', $fields);

$modx->runProcessor('resource/update', $fields);

$fields = array(
  'id'       => 42,
  'pagetitle'    => 'Example Page',
  'longtitle'    => 'Example - A New Document Created Through The Modx API',
  'alias'        => 'example-page',
  'description'  => 'Example description...',
  'template'     => 5,
  'published'    => 1,
  'content'      => '<p>This is some sample content.</p>',
);
 
$modx->runProcessor('resource/update', $fields);

//Add
$res = $modx->newObject('modDocument');
$res->set('parent',42);// parent or no
$res->set('pagetitle','New Title');
$res->setContent('This is your long text explaining about your pagetitle.');
$res->set('published',1);
$res->save();

//Update
$res = $modx->getObject('modResource',96);
$res->set('pagetitle','Change Title');
$res->set('content','<p>This is some sample contents.</p>');
$res->save();

//Remove
$res = $modx->getObject('modResource',96);
$res->remove();