When someone leaves the company, their accounts are often "forgotten" — email, cloud services, VPN, shared passwords. Such an account can end up in the hands of an attacker or a former employee.
An offboarding list typically includes: disabling accounts, changing shared passwords, handing mail and files over to a manager, returning the laptop and access cards, and removing MFA devices. The simplest approach is a ready-made checklist.
Example
On an employee's last day, IT disables every account using the checklist and forwards their mailbox to the manager.