In DPA, when choosing a monitored server, then wait status, and I can see a current tab on the top of the screen,
After clicking it, I can see currently active sessions and currently blocked sessions.
In the session ta --> Action --> kill sessions.
What privilege do I need to kill the sessions from here?
Within DPA, your login must have Admin privileges. In addition, the userid of the DPA connection to monitor a DB instance must also have appropriate DBMS permissions.