How to delete an IIS App Pool that is locked because apps are linked to it

 https://stackoverflow.com/questions/25814925/how-are-applications-removed-from-the-iis-application-pool

0. Go to folder
   cd C:\Windows\system32\inetsrv
1. List all applications to get the correct APP.NAME
   .\appcmd list app
2. Delete the application using fullname for <APP.NAME>.
   Ex.: "Default Web Site/The.Application".
   I mean, you must put it with web site name including the double-quotes.
   .\appcmd delete app <APP.NAME>