"The iPhone is already activated. You may disconnect this iPhone now" on iTunes 12.13.2.3. Desperately need help fixing my mistake.

Hi there,

A few months ago, I was trying to download the latest iOS, 17.1 I believe it was at the time. Since the download was insanely massive through the phone, I'd opted to try downloading it through iTunes. iTunes backed up my iPhone to my C:// drive, overfilling it and thus refusing to download the update. I tried fixing it through certain means and... I managed to turn on the activation lock on iTunes and I haven't been able to turn it off since. I've followed the Command Prompt recommendation, to no avail, and I did a full delete and subsequent re-install, per @turingtest2's guide, but that was an insane amount of work just to end up back to square one. Please, I just want to update my audio books (which Apple Music, the program, refused to do).

iPhone 12 Pro, first and only owner ever. Windows 10 PC, iTunes 12.13.2.3. I just don't want to go through the entire delete and reinstall process again.