O365 ATP - Ensuring Junk Email settings on Exchange Mailboxes are enabled for ZAP and Anti-spam

End users can disable junk folder in OWA
Click on the Options tool at the top right of the OWA page.
Click on See All Options...
Click on Block or Allow in the column on the left.
Click to select the Don't move e-mail to my Junk E-Mail folder option, which is at the top.
And the more techie end-users can connect to Exchange Online PowerShell and they can run this command against their own user mailbox.
You can prevent end-users from doing this by creating a custom policy, and you can also disable them from launching Exchange remote PowerShell:
for a single user: Set-User -Identity david@contoso.com -RemotePowerShellEnabled $false
for all users: get-user -resultsize unlimited | set-user -RemotePowerShellEnabled $false
(just be sure to exclude yourself and other global admins otherwise you'll lock yourself out.)
You can enable junk mail folder on all mailboxes with this one commnad:
$All = Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited; $All | foreach {Set-MailboxJunkEmailConfiguration $_.Name -Enabled $true}

If this was helpful, please mark as best answer. thanks!
-Joe