What is the process for cancelling an extension of stay based on employment in Thailand?

Cancelled my extension of stay based on employment in advance today at Chaeng Wattana. My contract finishes on the 31st of July. I checked with the IO regarding what was required on my last visit. It was not necessary to cancel my work permit which will be done next week. Required were the usual passport pages and a letter from my employer stating next Sunday the 31st as my final day of employment. Copies of my work permit were required as well as presenting the work permit book as well as passport. Photo of cancelation shown below.