Hide ModelAdmin sidebar in SilverStripe 3.x

cms.css

.cms .MyModelAdmin #cms-content-tools-ModelAdmin {
  display: none !important; }

config.yml

LeftAndMain:
  extra_requirements_css:
    - 'mysite/css/cms.css'

MyModelAdmin.php

<?php

class MyModelAdmin extends ModelAdmin {
	private static $managed_models = array('MyDataObject');
	private static $url_segment = 'foobar';
}