How to add Callback function for delete operation?
The operations are a list of links. If you want to delete a different entity see this example from the core workflows module how to build a delete link:

WorkflowStateEditForm::Form()

  $links['delete'] = [
    'title' =&gt; t('Delete'),
    'url' =&gt; Url::fromRoute('entity.workflow.delete_transition_form', [
      'workflow' =&gt; $workflow-&gt;id(),
      'workflow_transition' =&gt; $transition-&gt;id()
    ]),
  ];