eliminate all cronjobs using the ansible playbook

There are multiple ways. If you want to do it “correctly”, you set state: absent on all cronjobs and run the playbook:

  - name: Add in cronjob to run every 30 mins to update do cool things
    cron:
      name: "Run cool.py"
      user: cooluser
      state: absent

You need to set them for each cronjob you created, they are matched by name. Check the docs of the cron module.

If you just want to remove all the crontabs for a certain user, you can ssh to that box and run crontab -r -u cooluser. This will remove all jobs for cooluser, but leave everything in /etc/ untouched. But ansible does not add anything there.

If you want to do that, but use ansible, you can use the command module:

- name: remove all cronjobs for user cooluser
  command: crontab -r -u cooluser

The first one is the one you should use in a production playbook. The other two can be used, if you just want to do a one-time cleanup to start fresh.

You can also check crontab -l -u cooluser to see all currently available cronjobs and crontab -e -u cooluser to edit them.