Delete unnecessary groupadd in multinode-lab

Change-Id: I13c86a19c421d8ef102f35bcae63f6dc69317268
Closes-Bug: #1674897
diff --git a/doc/source/guides/multinode-lab.rst b/doc/source/guides/multinode-lab.rst
index 1b7f4cd..484ebba 100644
--- a/doc/source/guides/multinode-lab.rst
+++ b/doc/source/guides/multinode-lab.rst
@@ -73,8 +73,7 @@
 
 ::
 
-    groupadd stack
-    useradd -g stack -s /bin/bash -d /opt/stack -m stack
+    useradd -s /bin/bash -d /opt/stack -m stack
 
 This user will be making many changes to your system during installation
 and operation so it needs to have sudo privileges to root without a