We don't recommend deleting people unless they were created by accident. When a profile is deleted, all updates, tasks and milestones associated with that person are deleted as well.
If the profile represents a real person who has moved away, passed away or left your organization or for any other reason, you should archive the person instead.
Deleting A Person's Profile
Click the person you wish to delete
Scroll down to the bottom of the left hand page
Click Archive. The permanently delete button will now be visible.
Click Permanently delete
Read warning on how many updates, tasks and milestones will be deleted. Type in the the person's name to confirm deletion & click Delete person