The REST API provides the following method to manage the engine:

PUT /admin/engine

URI PUT /admin/engine
Description Stops the engine. This method cannot be called by the root administrator user.
Request Header  Content-Type: text/plain
CSRF Protection Enabled

Content-Type: text/vnd.orchestral.rhapsody.6_4+plain

CSRF Protection Enabled
Request Body STOP
Response Status 204 No Content - operation successful.
Response Body Empty.
Access Rights 'Stop engine REST API'