If a family has a remaining active student, balances owed, or have made payment's to an account you will want to see : How do I withdraw a student?  
Please also see: Are there drawbacks to withdrawing a student?

If a family has no active students, balances due, or payments made, you can Deactivate the family account to remove them from your active family list. See : How do I deactivate a family ? 

You will be able to reactivate at a later date if needed. See : How can I reactivate a deactivated family?