GitLab-CI: run job only when a branch is delete

In gitlab runner, I want to run job when the branch is deleted.

(.yml example)

creat job:
  stage: delete
  script:
    - echo 'branch delete'
  only:
   - ????

create:
  stage: delete
  script:
    - echo 'branch delete'
  rules:
    - if: '????'