How to delete a killed session?

@1

Hello,Scenario: Oracle RAC 11gR1 with 2 Linux nodes.

Using 'sys.show_blocker' I have detected a blocker user in the first instance.

    SESSID     SERIAL INSTANCE_ID
---------- ---------- -----------
      1365      52058           1
1 row selected.

I killed this session using:
ALTER SYSTEM KILL SESSION '1365,52058,@1' immediate.

Now this session is 'KILLED' but it is using database resources and 'sys.show_blocker' shows me the same session again as a blocker session.

How can I delete it?

Thanks in advance.