Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hello,
Thank you for your post.
Unfortunately there is no way around to delete Yammer network completely.
But to make Yammer free basic network as a enterprise network you need to add that Yammer free basic network domain in office 365 tenant and click on Yammer tile.
Now you will get verified admin rights as global admin of office 365 tenant becomes automatically verified admin in Yammer.
After this you can enforce office 365 identity and block the user without Yammer enterprise license under security settings in network admin. Once you enable this settings and remove Yammer license of users from office 365, so none of users will be able to login to Yammer network.
Being a verified admin you can delete all messages and files of Yammer network. After your office 365 subscription goes in expiry period then Yammer network disabled automatically.
Regards,
Sushil Dhiwa.
Microsoft Yammer support team.