An object of the type Microsoft.SharePoint.Administration.SPIisWebsiteUnprovisioningJobDefinition named “Unprovisioning TEST-PROD“already exists under the parent Microsoft.SharePoint.Administration.SPWebService named “”. Rename your object or delete the existing object.
A Long text error when you simply trying to delete a web application is something you won’t expect.
Ultimately the resolution for this is to delete the TimerJob exists as the error clearly mentions.
Open up the Central Administration and direct to Monitoring –> Review Job Definitions
Find the “Unprovisioning PRODTEST-INT” Job. Last part of the Job name will be based on your Web App Name.
Go ahead and click on it and then delete the Job. You should now be able to perform the deletion of Web Application.