Forum Discussion
Remove Office 365 Pro Plus Remotely from Personal Device After Employment Ends
After the user is terminated and the account disabled/removed, he cannot activate Office anymore, so he will not be able to add to the numbers of active installs. For users that are still active, you can go to the O365 admin portal, select the user and manage the office installs from there (remove devices that you don't recognize). Unfortunately, there is no programmatic way to do this, despite of us asking Microsoft for years...
If you want to tightly control who can install where, you will have to use some MDM solution (Intune) or disable the download altogether.
Very true that they cannot activate more licenses, but that does not stop them from using the applications without the license. They can still access anything in Outlook that was downloaded to their personal computer.