just for the record
i managed to delete the faulty index by:
- close faulty index
- give the faulty index a dummy alias
- delete Via dummy Alias and condition closed.
the main one won't be touched...
curl -XDELETE 'http://IP:PORT/test_index-test?expand_wildcards=closed'
where "test_index-test" in my case is the dummy alias assigned for the faulty index
Cheers