Yes, you can do this within the Diagnostics Console, though it has to be configured properly. This is done by updating a file in the app server's folder structure. You need to update the AppServer/Admin/sessionAdminSecurity.config file, to identify either Windows accounts or groups that have access to manage the session.
Then from the Diagnostic Console's main menu, select Tools, View Application Server Sessions. If the URL is correct, just hit Go, and if configured properly you'll get back a list of sessions. You can select and remove sessions from this window.
It can be clunky if you have a large number of users as the columns are not sortable. One workaround we used in the past was doing a select all, copy/paste the sessions into Excel, then search for the username you need to disconnect. This gives you a general idea of where they are in the list, so you know whereabouts to look in the Diagnostics Console.
The other option is to write some custom code. Both retrieving and disconnecting sessions is handled by a web service. If you reference it in code, you can build your own interfaces to find sessions. We did this to allow us to search across all app servers in a load balanced environment, allow column sorting, and allow for searching for a particular username across all servers. Now with a couple of clicks we can free up all sessions for a user across multiple servers.
