ExecutionEngine engine = (ExecutionEngine) new ExecutionEngine(graphDb);
try (final Tx tx = app.tx()) {
ExecutionResult result = engine.execute("start n = node(*) match (n)<-[r:ONE_TO_ONE]-() return r");
final Iterator<Relationship> rels = result.columnAs("r");
assertTrue(rels.hasNext());
rels.next().delete();