Doesnt look like you'll need too, looks like you'll have to delete the Profile for the beta. There are a few good topics about this in the main iOS 9 forum that goes into a little more detail. Hope that helps.
UPDATE: To be on the safe side, I'd make a back up just in case you have to revert back to 8.4.1. Then upgrade from there. I'm reading some conflicting information, at least if you have the back up, you know for sure you'll be able to do it that way.