Deleting a user in the portal

Deleting a user or many users are both mostly self-explanatory:

Deleting single/multiple user(s)

Microsoft warns:

"When you delete users, their data is deleted and their licenses can be assigned to other users. You can restore deleted users and their data for up to 30 days after you delete them."

That's quite true, unless the users are removed from the end user recycle bin for some reason. The most common reason for this is an administrator error, followed closely by unintended consequences of automated actions performed by AD Connect.

To delete a user in PowerShell, simply use the Remove-MsolUser command, like so:

Remove-MsolUser -UserPrincipalName "someuser@tenant_id.onmicrosoft.com"