I understand what you guys are saying about canceling an extension and cancelling a visa. But something needs to be canceled if you don’t want problems next time.
I left Thailand on an ED thinking I would never come back. I came back after the extension expired while I was in my home country. I could not get my new one until the old one was cancelled. I had to get letters from the ministry as well as my college to say that I don’t attend anymore.
You will have a problem if you ever come back and decide to go onto ED again! Trust me, happened to me. You can fix the problem if you decide to come back but it’s a mission.