Windows 7 Admin Can't Remove Files?

I hate for my first post to be about something there are tons of posts on already but nothing, so far, has done the trick.I'm trying to delete unused files from my computer.I'm running an HP desktop with Windows 7 Home Premium 32 bitFor a specific example, there is a Windows.old folder leftover from Vista, when I installed Windows 7. I would like to get rid of this folder. It originally had nearly 30GB in it. It would not delete as a folder. In frustration, I have gone through and deleted everything it would allow me to delete and am still sitting at nearly 13GB of wasted space. I cannot understand why I cannot be allowed to delete files off my own computer. I have logged in as adminstrator. I have given my normal user account administrator rights. I have activated the double secret extra special hidden administrator account. STILL...I am not allowed to delete files from my computer.'m not a programmer or any kind of computer tech guy. I'm an architect...not software architect...real architect. This is akin to me putting a refrigerator in your house that you can never remove. "Oh, it's broken and you need a new one? You'll have to put the new one next to the old broken one. Enjoy."

I have followed a bunch of the tutorials or instructions on going through properties, then security then advanced then owner back out, back in to properties back to security, then to edit then to permissions and every time there is something else telling me I need permission from something else. I swear one of them told me I needed permission from "Ron-pc/Ron" and that is what I am logged in as! My user account says:RonAdministratorPassword ProtectedOne of the biggest frustrations, next to it just not working, is that from the hidden administrator account I change the owners and permissions (All to "Administrator") and then I still get files that say I need permission from TrustedInstaller or SYSTEM or Ron as noted above. So they seem to be changed, but then aren't.