When an employee leaves the company permanently, you must delete his or her profile on the platform.
To do this, go to the Users tab and search for the person by typing their first and last name in the search bar.

Then you select the user and by clicking on his line, his description form appears. At the bottom of this one, you will see the Delete button. You just have to click on it to delete the user.

Once deleted, this collaborator will no longer have access to the platform and you will no longer see them in the list of users.