Does it show you as lacking certain permissions?

What about the "Replace all child object permission entries with inheritable permission entries from this object" in the advanced settings?

Try deleting the file/folder from an elevated command prompt.

You should note that there is a difference in newer versions of Windows between "The Administrator account" and a user who has administrative privileges (i.e. is a member of the Administrators group); the latter can perform privileged operations but will be required to confirm them.

Also note that in Windows an administrator account (of either flavour) doesn't automatically have access to all objects (but can gain such access by taking ownership of them). This is different from the UNIX world, where the root user has full access to all objects in the system. Windows security is more advanced in this respect.