There are a few different tools within SGA that allow you to see what users are logged into the system and end their processes.

Activity Monitor

This is a tool that shows what users are currently accessing the SQL server and how many processes they are running. It shows a summary of the processes with the SGA user, NT user, and Login or Windows user. A process is not how many times a user is logged in, but how many jobs the database is actually running for that user, which is normally several.

Right click a user to see all the processes for that user or click the Databases button to see a list of all databases or kill all processes for a database.

Processes

This shows processes, which is the most detailed level of activity in a database. There are also filters at the top of the screen to narrow down your results.

Databases

This shows a list of all SQL databases on the server and whether they are online or offline. Right click and select “Take offline” to take a database offline so that no one can access it for a period of time. Right click and select “Kill all processes for database” to kick any user out who is accessing that database.