Unassign an action item

{
  "actor": "jane@example.com"
}

{
  "id": "xYz789AbCdEf",
  "slug": "upgrade-base-image-to-fix-cve-2026-1234",
  "nrn": "organization=1:account=2:namespace=3:application=4",
  "title": "Upgrade base image to fix CVE-2026-1234",
  "description": "The current base image has a critical vulnerability.",
  "status": "open",
  "priority": "critical",
  "score": 2000,
  "category_id": "abc123def456",
  "value": 500,
  "created_by": "security-scanner-agent",
  "assignee_id": 2345,
  "assigned_at": "2026-08-20T14:32:00Z",
  "assigned_by": "jane@example.com",
  "due_date": "2026-05-01T00:00:00Z",
  "labels": {
    "source": "container-scan",
    "cve": "CVE-2026-1234"
  },
  "affected_resources": [
    {
      "type": "application",
      "name": "my-api-service",
      "permalink": "https://app.nullplatform.com/applications/4",
      "description": "Main API service"
    }
  ],
  "references": [
    {
      "name": "CVE-2026-1234",
      "permalink": "https://nvd.nist.gov/vuln/detail/CVE-2026-1234",
      "description": "NVD entry for this vulnerability"
    }
  ],
  "metadata": {
    "cve_id": "CVE-2026-1234"
  },
  "config": {
    "max_deferral_days": 90,
    "max_deferral_count": 3
  },
  "comments": [
    {
      "id": "cmt123AbCdEf",
      "author": "jane@example.com",
      "content": "This should be prioritized for the next sprint.",
      "created_at": "2026-04-06T14:30:00.000Z"
    }
  ],
  "audit_logs": [
    {
      "id": "3c35f973-d53b-4e60-a578-2e8fba1dbbb1",
      "actor": "jane@example.com",
      "action": "deferred",
      "details": {
        "from": "open",
        "to": "deferred",
        "reason": "Waiting for the next maintenance window."
      },
      "timestamp": "2026-04-06T12:00:00.000Z"
    }
  ],
  "created_at": "2026-04-06T12:00:00.000Z",
  "updated_at": "2026-04-06T12:00:00.000Z"
}