After installed iOS 9.x, the system always tell me new system level update, but I want keep the 9.x. Today found a way to stop system auto update function.

{ 1. Stop auto system update }

Use iPhone's Safari open << https://oldcat.me/web/NOOTA9.mobileconfig >> and install the Apple TV iOS 10 profile, it's 100% safe because it from apple.com. In short, the profile tell ios that it's an iOS 10 device, so do nothing for 10.x update.

Everything is fine for me.

{ 2. Delete downloaded file}

Setting - Gereral - Storage & iCloud Usage - (Storage)Manage Storage - Find download iOS update App - Delete

By this way, we can get a lot of free space

{ 3. Recover iOS auto-update }

Setting - Gereral - Profile - tvOS 10 Beta Software Profile - Delete

After Delete everything back to normal, Update, Update, Update, Update!!!

{ Ref }

https://www.zhihu.com/question/37297197