Is there a way to completely remove iOS from an iPhone and reinstall a fresh version manually?

Is there a way to completely remove iOS from an iPhone and reinstall a fresh version manually? - 1

Settings > Reset > Erase all content and settings will bring it back to factory defaults, but it doesn't reinstall iOS.

If you could erase (reformat) the memory, you would need to have a computer with iTunes to restore iOS. No way for the phone to go get the OS if you clear the current version off.

I wouldn't say you can really completely remove it however there's a mode called DFU mode done via a button combination that should fix almost any issue for you! Best of luck!

Geek Squad Agent Hunter S.
Badge # 104221

Advanced Repair Agent| Geek Squad Social Media Team
7/24/2017

DFU mode, as mentioned in another answer but not explained, will cause itunes to completely re-flash the whole operating system.

That overwrites the entire phone with a "clean" operating system image; all old data is totally erased.

When done, it starts up as if it were brand new.

(Though note that it's serial number is still in Apple's activation database, that is nothing to do with the phone content and reflashing does not allow you to remove the security; it still needs the username & password to get through activation if it is linked to an account so make sure you know them - it's whatever you use in the app store for purchases.).

Back it up first if you want to save the content. You can restore after the reflash if you want to put everything back.

It can fix various obscure faults & memory corruption that cause problems.

Details on how to do it:
https://www.payetteforward.com/how-to-put-iphone-dfu-mode/