@Ryan ***********
if you were in the first 90 days of the Ed Visa, you could just leave Thailand and the Ed Visa has ended.
It's when you get 90 days extensions for the Ed Visa which then requires it to be cancelled before you leave Thailand.
It appears that you got the university course of study arranged with both the university and possible Thai Visa Agent. And the Ed Visa continued with support of the Thai Immigration office.