In the Years Prior to Your Organization Moving to G

In the years prior to your organization moving to G Suite, it was relatively common practice for users to create consumer Google accounts with their corporate email address (for example, to monitor Analytics, manage AdSense, and collaborate in Docs with other partners who were on G Suite.) You were able to address active employees' use of consumer accounts during the rollout, and you are now concerned about blocking former employees who could potentially still have access to those services even though they don't have access to their corporate email account. What should you do?

A) Contact Google Enterprise Support to provide a list of all accounts on your domain(s) that access non-G Suite Google services and have them blocked.
B) Use the Transfer Tool for Unmanaged Accounts to send requests to the former users to transfer their account to your domain as a managed account.
C) Provide a list of all active employees to the managers of your company's Analytics, AdSense, etc. accounts, so they can clean up the respective access control lists.
D) Provision former user accounts with Cloud Identity licenses, generate a new Google password, and place them in an OU with all G Suite and Other Google Services disabled.