There could be a couple of reasons why you want to deactivate your Office 365 installation. Maybe you want to perform a fresh install Windows and Office on a new Solid State Drive, or perhaps you want to move your Office 365 to another computer activate it there. Or it could be that you have run out of Office 365 installs.
Luckily, deactivating Office 365 installation is relatively easy. You can deactivate your Office 2019, Office 2016, or Office 2013 installed as part of Office 365 subscription with ease.
If you want to deactivate and transfer an installation of Office 365 from one PC to another PC, simply follow the given below directions to deactivate your Office 365 installation.
Please note that deactivating Office 365 will not automatically uninstall it from the PC. You need to manually uninstall it if you want to get rid of it. However, it’s not necessary to uninstall Office 365 from your PC to complete the deactivation.
You will be able to open files with Office 365 applications even after deactivating it, but you won’t be able to edit files. Office 365 will continue to work in read-only mode.
Deactivate Office 365 installation
This method applies to Office 365 Home and Personal editions.
UPDATE in Feb 2020: Microsoft has replaced deactivating Office installs with signing out of them, but both are essentially the same.
Step 1: Visit this page of Office, and sign-in to your Office account using the email address that you used to subscribe to Office 365.
Step 2: The Devices section of the Install page displays all your computers where Office 365 is installed and activated.
Step 3: To deactivate an Office install, click on the Sign out of Office link next to the computer name. If Office is installed on multiple computers, we suggest you verify the computer name before clicking the Sign out of Office link.
To check the computer name, type Sysdm.cpl in the Start/taskbar search field and hit the Enter key. Under the Computer Name tab, you can find your computer’s name. Check this matches with the computer name shown on the Office page before clicking the Sign out of Office link.
When you sign out of Office installation, Office 365 will be deactivated on that computer.
Step 4: When you see the following confirmation dialog, click Sign out of Office button again to deactivate the Office 365 copy installed on the selected PC. The computer where you deactivated Office 365 will no longer be displayed on the Installs page.
How to download Office 365 offline installer guide might also help you.