To disable Clutter in Office365 via Powershell, simply do the following:

Connect to Office365 Powershell for your account

Then simply run this command to disable Clutter for all mailboxes:

Get-Mailbox | Set-Clutter –enable $false

That’s it! If you want to disable Clutter for a single mailbox, you can do the following:

Set-clutter -identity user@email.com-Enable $false

To do this via the Office365 Portal, just navigate to: Mail > Automatic Processing > Clutter and turn it off!