Yes, you can clear all ID's, passwords, fingerprint records, etc. as if the person had never used the checkin system.
For Family related people, locate the person then double-click their name to edit the person record; for employees, go to the employee Information and Relationship button (3 people icon).
When you see the
New Register button, hold down the
CTRL key on your keyboard (image below) and click the button. You will see a warning message that all checkin and registration information for this person will be removed.
Hold

and click