how to permenently delete a file using Developer 8.0?

Hi all,
I am facing this issue, a bit complicated to explain so here I put in point forms.

  1. I deleted a wsdl file (let’s call it wsdlX) from a wsdl folder which belong to a package.
  2. I successfully deleted that, due to the fact the wsdl is no longer visible, even after refreshed, log out log in etc.
  3. I then tried to create a wsdl name wsdlX and system now allow me, it gives me error that wsdlX file already exist. choose another name. If i choose another name it is fine. But to business reason I must use wsdlX filename. Also for learning purpose as well why I cannot re-use wsdlX filename.
  4. I then tried to delete wsdl folder, hoping wsdlX would get deleted too, but i cannot delete, error “Could not delete folder completely… Folder is not empty in package.” surely there is nothing in wsdl folder that I can see, maybe invisible.
  5. I have ensure all files are unlock, tried to delete still cannot.
  6. We have tried to stop IS, delete package out, deploy it back and still same error.
  7. We have ensured all dependencies (eg. port, credentials) aren’t there then tried delete and still cannot.

So my question is how can I delete a wsdlX file that is locking somewhere so that I can re-create it with same name.

Thank-you in advance.
Kind Regards