How to delete incomplete iTunes backups on windows?

I have very limited space on my pc, bummer, but that's just how it is. I recently downloaded the iOS 14 beta just to see what it was like. And please don't begin talking down on me, saying it was dumb etc. I'm 16 and want to have fun. In Denmark, we have a thing called NemID. Everyone over the age of 15 has it. And it's a universal login server, of which I need to see my bank account etc. However, I cannot use the '2FA' app they have, because they detect my device as jailbroken or rooted for security purposes. Therefore I want to downgrade. I was very happy with the beta though. From the tutorial I've watched, you need to backup your device on your pc to keep your data, which I want of course. And as I said, my pc didn't have near enough space for it, which I didn't think about. My disc went to 0 bytes available, and I couldn't locate the incompleted backup, neither on iTunes or in %appdata% I cleaned up a bit of space, and tried to select an iCloud backup on iTunes. To my surprise, it still backed up on my pc disc. I don't need an explanation or solution for this. But now i'm stuck with not having enough space for the ISPW file, and I can't find the backups anywhere. Sorry for the long description, but I just don't need any form of negativity, therefore I just gave context to the whole situation.

Thanks in advance.