Hi, so I went to the immigration and asked them when can I start to cancel my work permit and Non-B extension of stay. The officer told me I could cancel it 40 days before my extension of stay expires but will still be allowed to stay until the permitted to stay is finished which mine says March 14th. Considering what the officer said, I could cancel by start of February, right? Have you heard of anything like this before? Thanks for leading me to the right way.
TLDR : Answer Summary
You can cancel your work permit and Non-B extension of stay 40 days before the expiration date of your extension. According to the immigration officer, you can proceed with the cancellation at the start of February, and you will still be permitted to stay until your existing extension expires on March 14th.