Deleting Files Error

How do you delete a file that tells you “Cannot Delete Windows System Files or Files That Are In Use”. This is an audio file that won’t go away when I delet it. The error tells me to close a any programs that might be running it. I have checked everything and even booted in safe mode to try to delete this. I tried it from the command prompt. No luck. Any ideas on how I can delete this regardless of whether a program is “running” it.

Thanks