Received a "folder access denied" warning after wanting to delete a folder so I needed to change permissions on a folder. Changed it to - for example: "username (username-PC\username)". That was the "username" I was currently logged in as but strangely received the same exact "folder access denied" even though I had "permissions" on that folder.
It can be some application that has a lock on the folder. Download and install Unlocker Right click on the folder and click the unlocker menu item. There is a delete file option on the main screen.
Else you can use SysInternals Process Explorer to see which application has locked the folder.
EDIT: I recently came to know that Unlocker sometimes does not detect locks on folders by applications. Instead try runs the commandline tool Handles from SysInternals. This tool will also allow you to closing an open handle. (Caution: Closing an open handle MAY cause a system crash in some cases.)
You say you took ownership of the folder; did you also change the permissions? Being the owner does not in and of itself allow access to a file or folder, although it does allow you to read and set the permissions.
(Note that under some but not all circumstances the GUI will change permissions automatically when you take ownership of a file/folder.)