Contacts Management when employees resign from accounts..

Contacts Management when employees resign from accounts..

Need a best practice suggestion from other users...
Should we delete the contacts associated with a respective account, when the employee has left the organization? Or should we retain the same.. 

If we delete it, then what happens to all the past emails, sales orders, activity associated with that particular contact.

If we do not delete it, then our sales team gets confused and sends the email campaign mailers to them or call them..

Rajesh K Kishanpuriya
Ideazfirst Marketing Services (P) Ltd
Kolkata, India