How many days can I stay in Thailand after canceling my visa with the university?

I have no clue what "all done and fixed as per CMU" means, however it sounds like the problem is solved. I'm closing comments. If anyone wants comments reopen, please send a mod a message.

the way he worded that question, he might be on ED extension

When you cancel your extension of stay based on employment, you have until 11:59PM THE SAME DAY to leave Thailand to avoid being on overstay, or to apply for another extension of stay.

IF your current and future employer, and the immigration offices are willing to work together, you can cancel your existing extension of stay based on employment with your old employer, and then AT THE SAME TIME, apply for a new one year extension of stay based on employment.

If, for some reason, you can not do this, you *MAY* be able to apply for a 60 day extension of stay based on unable to travel due to COVID-19. I don't know if you can go from that 60 day extension of stay based on COVID-19 to a one year extension of stay based on employment though.