You can delete an index using the dsconfig tool. Check that no plugin applications are using the index before deleting it. When the index is deleted, the corresponding index database will also be deleted. The disk space is reclaimed once the cleaner threads begin.
Use dsconfig with the
delete-local-db-indexoption to remove it from the database.
$ bin/dsconfig delete-local-db-index \ --index-name roomNumber --backend-name userRoot