Do no harm to a company when leaving.
Explanation:
HR knows about work-related websites, for example, payroll systems, Go to Meeting accounts, software accounts and travel services for most of our workers. It doesn't really matter if HR pulls the keys for these logins or IT–as long as someone takes care of this, and there is a process in place to turn things off. 
For example, one have been informed by one IT professional of a case when a senior person was released from accounting. In the first step, access to all IT services was eliminated (Two minutes before the HR sent HR the incorrect news), passwords changed on external site, and business hardware inventory (BlackBerry, mobile, building access cards) was deleted. IT also required the CFO, which had to notify the banking systems that the employee was no longer authorized to act for the company's sake, to make email records available.