What is the process for obtaining a cancellation letter from Chiang Mai University?

I have been through this process in Chiang Mai University (CMU). We applied in the

College administration for a cancellation letter. It took a couple of days. Then it had to be signed off by the head of department which took another few days. So we were running back and forth until it was finalized.

All I can say is, don’t leave it to the last minute.