@Test
    public void shouldRemoveUser() {
        final Graph graph = TinkerGraph.open();
        final CredentialTraversalSource g = graph.traversal(CredentialTraversalSource.class);
        assertThat(graph.vertices().hasNext(), is(false));
        g.user("stephen", "secret").iterate();
        assertThat(graph.vertices().hasNext(), is(true));

        g.users("stephen").drop().iterate();
        assertThat(graph.vertices().hasNext(), is(false));
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-groovy/src/test/java/org/apache/tinkerpop/gremlin/groovy/jsr223/dsl/credential/CredentialTraversalDslTest.java