Datapump jobs in defining state

Hi experts.I have the following datapump jobs in definig state and i wish to delete them.
Also would like to know what is this, why they came into this state and how can avoid this in the future:
OWNER_NAME JOB_NAME             OPERATION   JOB_MODE    STATE       ATTACHED_SESSIONS
---------- -------------------- ----------- ----------- ----------- -----------------
BACKUP_USE SYS_EXPORT_FULL_59   EXPORT      FULL        DEFINING                    0
R

BACKUP_USE SYS_EXPORT_FULL_60   EXPORT      FULL        DEFINING                    0
R

BACKUP_USE SYS_EXPORT_FULL_61   EXPORT      FULL        DEFINING                    0
R

BACKUP_USE SYS_EXPORT_FULL_62   EXPORT      FULL        DEFINING                    0
R

BACKUP_USE SYS_EXPORT_FULL_63   EXPORT      FULL        DEFINING                    0
R