Uninstall doesn't work - any ideas?

Hi - I read the manual regarding uninstallation, and followed the instructions to run Uninstall.sql. However I get a bumch of errors. Does anyone have any ideas?

I'm not a DB wizard - hence exploring the application. I am logged into DB using Oracle SQLDeveloper as sysadm, the Db version is 10G. I am running it on my laptop.

The DBMonitor job is lkilling my laptop, which is my main reason to uninstall.

Error starting at line 15 in command:
DROP USER ora_monitor CASCADE
Error report:
SQL Error: ORA-01940: cannot drop a user that is currently connected

Error starting at line 16 in command:
DROP PUBLIC SYNONYM db_alert
Error report:
SQL Error: ORA-01432: public synonym to be dropped does not exist

Error starting at line 20 in command:
EXECUTE DBMS_IJOB.DROP_USER_JOBS('ORA_MONITOR');
Error report:
ORA-06550: line 1, column 7:
PLS-00201: identifier 'DBMS_IJOB.DROP_USER_JOBS' must be declared
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

Error starting at line 23 in command:
{
Error report:
Unknown Command

Error starting at line 24 in command:
FOR rec IN (SELECT job FROM sys.dba_jobs WHERE upper(what) LIKE 'ORA_MONITOR.%') LOOP
Error report:
Unknown Command

Error starting at line 25 in command:
DBMS_JOB.BROKEN(rec.job, TRUE, SYSDATE);
Error report:
Unknown Command

Error starting at line 26 in command:
END LOOP;
Error report:
Unknown Command

Error starting at line 27 in command:
}
Error report:
Unknown Command

Many thanks

As the first error suggests, you have an active ORA_MONITOR connection. Please find out who is using it and close it, then run
DROP USER ora_monitor CASCADE

Make sure you connect to the database as SYS when executing this command, and last if you are going to do this from SQL*Plus or other non-DB Tools editor, don't use {} brackets around PL/SQL blocks, paste the entire block beginning with "DECLARE" and ending with "END;" to the SQL*Plus then enter / on a new line and then press the enter key.