Windows 7 - access denied when I delete files in safe mode admin

Hello,
I have an external drive which I'm trying to reuse as a storage only medium. It's a usb drive on which at one point I managed to install a limited version of windows xp,to run on my first netbook (which I no longer use). I have put other stuff on the drive so I don't want to format it, but there are two files I can't get rid of.They are macromedia flash files. (ocx and exe). I tried taking ownership, running cmd adminstrator, going into safe mode with command prompt, and running admin powershell. I can see the attributes - A and R but I can't change them. I've also tried deleting them via filemenutools delete locked files, but that does not help me either. I want them gone, can anyone help me? I've read one other post where the OP had the same problem, but his problem was solved because his antivirus program eventually decided his file was a virus and got rid of it. So it is possible, but I can't find what to do. I guess it's not a big thing but it bothers me that I'm not able to remove these files no matter what I do. Help would be appreciated...

I would just reformat it personally. Start from a clean slate.

Maybe I'll still do that, if I can't get rid of those two pesky files, but I'm still wanting to know how I can delete them, and why the system won't let me. I tried hooking it up to an xp system, got the same problem. When I try to delete them the error message says they are open in another application. When I went to all those command shells it just said access denied, even when I logged on as administrator. And even in safe mode admin cmd I could not change the attributes. That's weird.