If you wish to stop getting iOS beta updates, just go to Settings > General > Software Update > Beta Updates and select Off. If you have a personal Apple ID you wish to use for all your iOS activities and services, but a separate Apple ID registered as a developer, you use your regular Apple ID on your iPhone and select Apple ID on the Beta Updates page to supply your registered developer ID just for beta access. You must be logged in to the Apple ID that is enrolled in the Apple Developer Program, which costs $99 a year. Future updates will appear in General > Software Updates unless Off is selected. If there’s a beta available, it will now appear and you can then download and install it. Select the one you want and return to the previous screen. Tap it and you’ll see three options: Off, Developer Beta, and Public Beta. Then go to Settings > General > Software Update and you’ll see a new tab for Beta Updates.

You’ll have to sign in with your Apple ID and agree to some terms and conditions. To get started in the beta process, whether you’re a developer or a curious user, start by visiting the Apple Beta Software Program site and enroll in the iOS public beta program.

Apple beta profiles