How do I undo the damage of a beta iOS and downgrade to the latest public iOS?

By uninstalling the beta software version, as per these instructions:--> How to uninstall iOS or iPadOS beta software

For any further questions about this matter, please contact Apple Beta Software Program, or join Apple Developer forums.

Regards

Giulio

If you installed the Public/Customer beta, Apple will not provide you any support on resolving issues doing so. That was clearly stated when you elected to install the beta software. On the other hand, if you are a member of the Apple Developer Network and installed a Developer beta version, you should already know how to contact Apple for assistance.

Regardless, you can still try contacting Apple Support if you want to. I'm pretty sure that they will tell you the same things as the two other responders have been telling you. Anyway to reach Apple Support, just select the "Support" link on the lower left-hand side of this forum's web page.

To your original question, in order to remove the beta and install the latest released version, you will need to restore your iPhone. That process will completely erase it and requires that you have a Mac to actually accomplish that. Since you don't have one handy, you may want to consider asking a friend or relative to see if you can borrow one from them. Alternately you can visit your local Apple Store or Apple Authorized Service Provider for assistance with this. Regardless, you will not be able to resolve the data loss for those last six months.

Ref: Apple Beta — Restore Shipping Software

We can only help you so far because of the non-disclosure agreement that people agree to when joining the beta test program. We can’t discuss beta problems in this public forum. We can send you here: Apple Beta — Unenroll Your Devices

Then you will not be able to restore all your data. You will only be able to get back whatever was stored in the backup 6 months ago.

Sorry there is no way to maintain all your data at this point. Installing Betas should only be done by people prepared to handle the issues and problems it will not doubt have and cause. It is not a public release, and is not meant for the general user base to install.

We cannot discuss the Beta here any further as it is not allowed per the NDA and terms of the Beta you agreed to when installing it. Sorry.

Apple Beta Software Program

Is the public beta software confidential?

Yes, the public beta software is Apple confidential information. Don’t install the public beta software on any systems you don’t directly control or that you share with others. Don’t blog, post screen shots, tweet, or publicly post information about the public beta software, and don’t discuss the public beta software with or demonstrate it to others who are not in the Apple Beta Software Program. If Apple has publicly disclosed technical information about the public beta software, it is no longer considered confidential.

Read our Terms for full details

 No Support and Maintenance; Future Products. During your participation in the Beta Program or in a particular seed, Apple is not obligated to provide you with any maintenance, technical or other support for the Pre-Release Software. If, at Apple’s option, such support is provided, it will be provided in addition to your normal warranty coverage for your computer and/or device. You agree to abide by any support rules and policies that Apple provides to you in order to receive such support. You acknowledge that Apple has no express or implied obligation to announce or make available a commercial version of the Pre-Release Software to anyone in the future. Should a commercial version be made available, it may have features or functionality that are different from those found in the Pre-Release Software licensed hereunder.

We (you) cannot discuss about Apple Beta Software in this public forum, as per NDA that we (you) accepted, sorry.

After performing the steps I provided in my previous reply, for any further questions, as already stated, you must contact Apple Beta Software Program, or an Apple Developer Forum.

Regards

Giulio

Tesserax wrote:

If you installed the Public/Customer beta, Apple will not provide you any support on resolving issues doing so. That was clearly stated when you elected to install the beta software. On the other hand, if you are a member of the Apple Developer Network and installed a Developer beta version, you should already know how to contact Apple for assistance.

But if they installed the Developer beta without being part of their Apple Developer Network, then Apple will also not offer any assistance or support.

The fact they are posting here with this issue, is a fairly good indicator they acquired the beta outside of the proper channels. Which again, precludes us from helping beyond posting the removal instructions.

Beta | Apple Developer Forums

Good point! Thanks.