Here is a quick example of how to disable to Lync / Skype for Business User

Open Windows Power Shell –  In my case I use Windows Powershell ISE – These steps need to take place on the Lync server host itself.

# Example: disables Lync user account
# Lync now known as Skype for Business
Get-CSUser -Identity "Jermal Smith"
Disable-CsUser -Identity "Jermal Smith"