If you have been running betas, you need to delete the beta profile from your phone (Settings > General > Profile).
I might be wrong here but, since the build you already have is the same as today, you probably won't be prompted to install the new iOS 11 GM release.
If you want to start brand new, fresh, you can manually download the iOS GM, connect your phone to iTunes, wipe the phone, initiate DFU mode and point to the IOS 11 GM you downloaded. That will install iOS 11 on your newly wiped phone. If you have a computer or iCloud backup from before your betas, you can restore from backup. If not, you will need to manually install all your apps if you don't want to use one of the beta restore points.
If you haven't already been doing so, make sure and do regular encrypted backups via the computer as well as iCloud, especially when running betas. Makes it easier to restore to pre-bata when you have the encrypted backup.