Follow the steps below to remove someone as staff:
Go to Configuration > Staff and resources > Staff > find the person you want to remove
Click on the profile and go to the "Staff" tab
Check the "No longer employed" box and set a date for "End of employment" > Save
Close the window of the selected profile > From the list, mark the person and press "Remove from staff"
Once this is done, follow the steps in the article below to remove the profile from the database completely: