Remove whoami.yml, it's now done by delegate_to.yml.

examples/playbook/whoami.yml

----
-
-- hosts: all
-  tasks:
-  - name: "This command should run as the SSH user"
-    command: whoami
-    register: whoami
-
-  - name: "Verify non-become user is correct"
-    assert:
-      that: "whoami.stdout == '{{ansible_user_id}}'"
-
-  - name: "This command should run as root"
-    become: true
-    command: whoami
-    register: whoami
-
-  - name: "Verify become user is correct"
-    assert:
-      that: "whoami.stdout == 'root'"
-