Which jobs are working?

SQL> select job_name, session_id, running_instance, elapsed_time, cpu_used from dba_scheduler_running_jobs;

Stop the job using

SQL> exec DBMS_SCHEDULER.stop_JOB (job_name => 'JOB_DEL_PROJECTS');

Set all jobs to zero

SQL> 
SHOW PARAMETER JOB_QUEUE_PROCESSES
alter system set JOB_QUEUE_PROCESSES=0;
SHOW PARAMETER JOB_QUEUE_PROCESSES