I opted to build a tile cache manually, published the web layer, and started the build from Portal.
About 10 seconds later I realized a layer was turned off so I need to cancel the build and publish again.
I tried to delete the service in Portal so that I could republish it, and it won't let me, I just get the ubiquitous "ERROR" message.
I am assuming the in-progress cache build is stopping the deletion? Delete is probably too stupid to kill the build and it's keeping the files locked.
Is there a way to kill the build operation from the server?