Deleting Xcode

I'm trying to delete Xcode 9. I dragged the application to the trash and tried to empty it. It seems to have deleted most of the app but then stopped. I can't delete the remainder - there's still an app icon with a grey slash over it in the trash. When I try to delete it I get this dialog:

I follow the directions and check the file info. The file is not locked and I have read and write access.

How do I delete this app?

Also, after I delete the app, is there any other extraneous data I can delete along with it?