i need to disable lync for all users to prepare for decommissioning the on premise lync server after migrating all users to office 365, is there a command or a script to help on that

Disable-CsUser -Identity <UserIdParameter> [-Confirm [<SwitchParameter>]] [-DomainController <Fqdn>] [-PassThru <SwitchParameter>] [-WhatIf [<SwitchParameter>]]

https://technet.microsoft.com/en-us/library/gg398747.aspx?f=255&MSPPError=-2147217396

this might help you 

Hi MAHER0,

You can run the following cmdlet in Lync PowerShell.

Get-CsUser | Disable-CsUser

Best regards,

Eric