By default, modules are run against your managed nodes (the target systems). The delegate_to parameter can be used to run a module on the control node (that's your Ansible server). Refer to these articles for a better understanding of how tasks are run against the control node or managed nodes.

• Run tasks on the control node
• Run tasks on your managed nodes

In this example, the delegate_to parameter is used with the file module to remove a file on the control node.

- name: remove foo.txt on control node
    module: file
    path: /tmp/foo.txt
    state: absent
    delegate_to: localhost

Often, the run_once parameter is used so that the task is only ran one time on the control node.

- name: remove foo.txt on control node
    module: file
    path: /tmp/foo.txt
    state: absent
    delegate_to: localhost
    run_once: true

Running this task should produce the following.

TASK [remove foo.txt on control node] 
changed: [server1.example.com -> localhost]