Some of the questions we often get is, "What do I do to protect data when an employee leaves the organization?" and "How do I block a former employees access to Office 365 after they leave?" This topic discusses the steps you should take and how to secure your data after an employee leaves your company. Office 365 admins can choose how to handle a user's Office 365 data and subscription when the user is in the process of leaving or has left your organization.
Continue at source: https://support.office.com/en-US/article/How-to-block-employee-access-to-Office-365-data-44d96212-4d90-4027-9aa9-a95eddb367d1