Illustration of a phone with yellow caution tape running over it.
But doing so obviously leaves your phone unprotected.
Photo by Amelia Holowaty Krales / The Verge

It is possible to remove the security patches installed by the Rapid Security Response system without having to restart your phone. If you want to remove a Rapid Security Response update, you can do it by going to settings > general > about, then tapping on the version you want to remove. You can remove the security update from there.

There are no examples in the document of why you would need to uninstall a patch. It is easy to imagine a few special circumstances in which the feature could be useful. It is one of those features that most people should never use unless they have a specific reason and fully understand what they are doing.

It’s nice to have control, but most people shouldn’t need it

You can turn off the updates by going to settings > general > software update > automatic updates andggling "security responses and system files." You will have to wait for full updates to get the patches. Unless you have an explicit reason to do so, I would recommend against turning the feature off.

It hasn't been officially released yet, but Apple's support documents for its desktop OS don't mention whether you'll be able to roll back those updates as well.

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