Last time I create WAS profile and WASService then I try to config and run many script for learn how to config WAS, Finally it crash so i use wasprofile delete this profile
I had this error also, make sure the exe the service is pointing to is stopped. Also make sure you don't have any Windows dialog boxes behind your other windows. That is why mine wasn't deleting. There was a windows message behind it saying this service has been deleted or something similar.. just had to click ok, there it went.