What should my girlfriend do after canceling her extension of stay and work permit in Thailand before leaving the country?

Canceling extension of stay / work permit. My girlfriend resigned from her job and next week Friday 30th of March is her last day. She is flying out 5 days later on the 4th of April. The school asked her to go with them to immigration to cancel her extension of stay / work permit on Tuesday 27th of March. This means after they cancel everything she will leave Thailand 8 days after the cancellation if she goes on Tuesday with her school. From what I have read and how I understand it she has to leave within 7 days once they go cancel everything. In the comment section is her stamp. Any advice would be appreciated :-)