-- If you cannot attach to a datapump job to kill it, you will need to drop the master table associated with it.

-- 1. Locate the master table:

SELECT o.status, o.object_id, o.object_type, 
       o.owner||'.'||object_name "OWNER.OBJECT" 
  FROM dba_objects o, dba_datapump_jobs j 
 WHERE o.owner=j.owner_name AND o.object_name=j.job_name 
   AND j.job_name NOT LIKE 'BIN$%' ORDER BY 4,2; 

STATUS   OBJECT_ID OBJECT_TYPE  OWNER.OBJECT 
------- ---------- ------------ ------------------------- 
VALID        85162 TABLE        SYSTEM.SYS_EXPORT_FULL_01

-- 2. Drop the master table 
DROP TABLE SYSTEM.SYS_EXPORT_FULL_01;