You can remove the ability for users to use the Instant Messaging channel by removing the channel from the user\qs display profile. For example, to remove the sample IMChannel that is automatically installed, do the following:
From an Internet browser, log into the Portal Server administration console at http://hostname:port /psconsole, for example http://psserver.company22.example.com:80/psconsole
Click the Identity Management tab to display the View drop down list in the navigation pane.
Select Services in the View drop down list to display the list of configurable services.
Click the arrow icon next to the Portal Desktop service.
Click the Manage Channels and Containers Link.
Select the check box to the left of the IMChannel channel.