How do I remove an invitation request notification?

I'm using FB.ui({method: 'apprequests', ... }) to invite a user but when the user accepts and logs into the app, the app icon still has a little red 1 on it. How do I remove this notification or even get a list of notifications? I've tried querying the graph explorer with manage_notifications permissions but I always end up with an empty data array.

I'd like to do as much as possible using the graph API and php if that's an option.

This is covered thoroughily in the requests documentation. You would just need to issue a HTTP DELETE command to https://graph.facebook.com/requestID?access_token=... The id's come as part of the querystring when the user clicks on the notification: https://apps.facebook.com/[app_name]/?request_ids=[request_ids]