curl -X DELETE "https://app.talkover.ai/api/v1/phone-numbers/release-requests/request-uuid-1" \
  -H "Authorization: Bearer talq_your_environment_token_here"

{
  "success": true,
  "message": "Release request cancelled"
}

{
  "success": false,
  "message": "Release request not found"
}

{
  "success": false,
  "message": "Release request already resolved and cannot be cancelled",
  "code": "RELEASE_ALREADY_RESOLVED"
}