Turn off OWA for specific users

I have been trying to do this for a little while

So I added testacct1 and testacct2 into exchange and simply disabled OWA through the ECP – I thought you know … it would work.  It does not.  I found some powershell commands as well but none seem to work yet. 

Get-Mailbox –Identity <username> | Set-CASMailbox -MAPIBlockOutlookRpcHttp:$True

Get-Mailbox –Identity <username> | Set-CASMailbox -OWAEnabled $False

Get-Mailbox –Identity <username> | Set-CASMailbox -OWAMobileAppEnabled $False

Set-CASMailbox <username> -OWAMobileAppEnabled $False

None of those disabled anything.