Tried everything but couldn't get away with the Access denied issue on Windows 7. Try this -
1. Access Start -> Command Prompt
2. Run "Command Prompt" as administrator ( right click and click run as administrator )
3. Execute "net user administator /active:yes" on the command prompt to enable the default Windows 7 Adminstrator account.
4. Restart the system and then log in using just enabled administrator user.
5. Access / Delete the Folder.
You can disable the default admin user by following command
net user administator /active:no