Hello, if an employee leaves the company, when he leaves the DingTalk enterprise structure, he will be automatically move out from "Department Group" and "Secured Enterprise Group", and General Group chat will not be affected;
If an employee withdraws from a department but does not withdraw from the company, the employee will automatically exit from the "Department Group" and will not exit from "Secured Enterprise Group and General Group".

Guess you want to learn more about:
How to exit group chat？