Permissions / Ownership And An Undeletable Folder

Im in the process of spring cleaning my big stack of hard-drives, in preperation for doing a clean windows install onto my shiney new Kingston V100 SSD.I'm currently looking at one of my 2TB external archive drives, which used to be the system disk on my media-server but is now just an archive disk. Anyways, on that drive, I found a windows folder (no big shock for a system disk) and I figured that I don't need that, as I've previous migrated all the user files when I took it out of the old machine.So I went to delete it, and it told me that I needed permission from 'S-1-5-21-432763403-189175183-190391661- 1000' to delete the folder. From there, I went to the permissions tab, figuring that I'd just have to give myself the rights to get rid of it. No dice there, I couldn't change any permissions, or add or remove users. From there, I went over to the advanced tab, figuring that I could take ownership and from there get the rights I need.

'You do not have permission to read the contents of E:etc etc, do you want to replace permissions with permissions granting full control?' dialogue, so I hit yes, which brought up:'An error occurred while applying security information to E: Access is denied.' None of the ownership, nor permissions changed, so I still can't get rid of anything in the folder. So, what do I have to do to get rid of this thing? Sure its only 20gb on a 2tb disk, but its clutter and I want rid of it! There is a possibility that this was a botched install of windows, rather than a full one (i know it happened once, but I can't remember if it was this one or a different drive), which I guess might explain why the permissions are all hinky, but either way, I wanna know how to clean it out.