Where/How can I delete or flush SMS/MMS database for my unrooted Nexus 4?

I have a stuck SMS/MMS, it won't disappear, I've deleted the thread, all my SMS from the messenger application. But my GlowFly app is still pulling one old MMS as a notification. I contacted the developer and he said the app read the database so there must be a corruption in the sms/mms database and to clear it. But I don't know how..

I've looked for the mmssms.db and can't find it anywhere. I've looked in data/data and nothing. So...

1) Where is it on my Nexus 4 4.2.2 JB unrooted
2) How do I get there?

Thanks everyone!