"Roaming -> Apple Computer" is taking up 43% of entire hard drive; is it safe to delete?

Question

My laptop (running Windows 10) has 223 GB of available storage and has been mysteriously filling up over the course of several years. Often, after backing up my iPhone to an external drive using iTunes (installed on this computer), my computer would completely fill up afterward despite iTunes' storage space being relatively small.

I've tried uninstalling and reinstalling iTunes several times, but this didn't help. I finally uninstalled it again and went through my C drive folders one at a time and discovered iTunes apparently isn't deleting the following folder (I told it to remove all files during the uninstall):

C:\Users\[username]\AppData\Roaming

which is now using 96.5 GB of space (43% of all my available storage), despite the software and its files ostensibly being gone. Can I safely delete these files without screwing anything up? I don't care about the backups because I back them up manually.

Is there a way to use iTunes on my computer such that it won't clog up with misplaced backups? Or should I only install it on my external drive?

And more importantly, is there a way to ensure that the space used by this folder is accurately represented under App storage usage?

Answer 1

(Technically, this is a Windows question, but there’s enough overlap to address it here)

  C:\Users\[username]\AppData\Roaming

which is now using 96.5 GB of space (43% of all my available storage), despite the software and its files ostensibly being gone. Can I safely delete these files without screwing anything up?

Do not delete this file!

This is not specific to iTunes or your Apple device. It is what keeps all your apps synchronized across devices. From the Windows Developer Blog:

Roaming app data

Roaming app data is the way in which all Universal Windows Platform (UWP) apps keep data in sync across multiple devices. It allows you, the developer, to create apps that help users carry data such as user profiles or documents from one device to the next.

^{Emphasis mine}

By deleting this file you’ll affect other apps that you sync between your Windows machine and your other devices (laptop, iPhone, iPad, Android Tablet, etc.) You could lose data or at the very least, have different versions of documents, settings, etc. between all your devices.