Hello, my ED visa will expire soon (was learning Thai language for the last 12 months).
Can anyone tell me if I need to cancel it before leaving the country?
TLDR : Answer Summary
Yes, you need to officially cancel your ED visa before leaving the country. It's important to obtain documentation from your school confirming your end of study date, then visit the immigration office about a week before your visa expiry to cancel it properly. Simply exiting the country will not cancel the extension and could affect future visa applications.