Hi, try to take a look at this post - https://support.apple.com/en-us/HT203282 from Apple Support on how to properly uninstall iOS beta software. It seems you have to wait the next update to get back to a non beta version of the OS.
You can also find a lot of guides on the Internet that explain how to do it step by step.
Topic:
App & System Services
SubTopic:
Core OS
Tags: