I moved one of my (single-file) externals to another directory, but its presence persists in my working copy. If I delete the file and then svn update, it gets restored.
How can I get rid of the external? It's no longer present in svn:externals in the directory in question.
This is a known problem, see:
http://subversion.tigris.org/issues/show_bug.cgi?id=3351 - can't remove file externals.
It was fixed in 1.7, but in 1.6 one has to checkout a fresh working copy to get rid of the file.