Flarum\Extension\ExtensionManager::disable PHP Method

    public function disable($name)
    {
        $enabled = $this->getEnabled();
        if (($k = array_search($name, $enabled)) !== false) {
            unset($enabled[$k]);
            $extension = $this->getExtension($name);
            $this->setEnabled($enabled);
            $extension->setEnabled(false);
            $this->dispatcher->fire(new ExtensionWasDisabled($extension));
        }
    }

 protected function delete(ServerRequestInterface $request)
 {
     $this->assertAdminAndSudo($request);
     $name = array_get($request->getQueryParams(), 'name');
     $this->extensions->disable($name);
     $this->extensions->uninstall($name);
 }