You can change the access and role from both current employees and past employees:
  1. Navigate to Core > People Finder
  2. Search for the user and select their name
  3. Select Access
  4. Click Employment
  5. Click Edit
  6. Select Employ in the top right corner
  7.  Mark the button Effective Immediately and mark one of the school levels
  8. Click  Save & Exit
To withdraw a user, follow steps 1 - 5, then
  1. Scroll down to the bottom of the page and enter the Effective Date/Time of withdrawal
  2. Mark Disables the user's login credentials 
  3.  Save & Exit
To edit the user's Depart Date:
  1. Navigate to Core > People Finder
  2. Search for the user and select their name
  3. Select Access
  4. Click Employment
  5. Click Edit
  6. Edit the Date Departed at the bottom of the page
  7. Save & Exit