Hi Sirichai,
Thanks for sending the proof of purchase for this product:
Product: iPhone 4s
Serial number: DX4HW154DTD2
After reviewing the documentation you provided, we unlocked the product.
If you need help with your device, please contact Apple Support. Just choose a topic and we’ll find you the best support option:
https://getsupport.apple.com
For more information on Find My iPhone Activation Lock, see this article:
https://support.apple.com/en-gb/HT201365
Thanks,
Joan
AppleCare Account Security