Open Dismiss notifications created by Join API?

Is there a way to dismiss notifications that were created using the Join API via a url? I have a script that posts notifications to my Chrome Join extension, but they're only really relevant for a few seconds and I'd like them to dismiss when they're no longer relevant so my notification list doesn't get cluttered with lots of messages. Is there a way to either set a timeout for notifications to automatically dismiss, or else use the url api to clear previous notifications? I'd prefer to be able to set some kind of timeout, like 10 seconds or something, so I only see the notification while it's relevant and it disappears when it's not needed anymore, without me needing to manually dismiss it each time.