To kill a session in OEM level,
Login to the OEM > Go to the Targets> Select the database > Click on Performance > select Search Sessions (in Additional Monitoring Links) > In the Search filter give the Sid if you know otherwise press the Go button it will list out all the sessions then select the required sid > Click on kill session button > it will ask for the Confirmation, Select the Kill Immediate button then Press Yes > Then you will get
ORA-00031: Session marked for kill error.
Then the session is no more exist in the database.
Happy Learning :)
Login to the OEM > Go to the Targets> Select the database > Click on Performance > select Search Sessions (in Additional Monitoring Links) > In the Search filter give the Sid if you know otherwise press the Go button it will list out all the sessions then select the required sid > Click on kill session button > it will ask for the Confirmation, Select the Kill Immediate button then Press Yes > Then you will get
ORA-00031: Session marked for kill error.
Then the session is no more exist in the database.
Happy Learning :)