You can stop iOS updates from installing even after the installation process has started. Although there is no button to make this easy, you can do it if you know the right tricks. This article will show you how to stop an iOS update in progress.
How to cancel an iOS update!
There are two parts of the iOS update process where you can stop the update: during the download and during the installation. That’s because over-the-air iOS updates are a two-step process: the iPhone first downloads the iOS update file to your iPhone before installing it.
There is no button to stop an ongoing download, so you will need to temporarily disconnect your iPhone from the Internet. To stop the update file download itself, even if the download is partially complete, follow these steps:
Open the Control Center (by swiping down from the top-right corner on iPhone X and later, or by swiping up from the bottom of the screen on older models).