If you have deleted a user from Office365 and it's still showing up in O365 Backup, you can follow the steps below in order to remove that user from the list.
- Firstly, this user must not have any backup data. If you wish to completely remove the user, firstly you need to delete all backup data for the User, as documented here.
- Once Backup Data has been deleted - allow some time for data to be deleted completely. After that, you should now see the option under [Backups] > [Users].
Once you have located the user, click the options menu next to the user and then click on [Remove the User from the list]