On Unix systems, there's a command named kill that you can use to send any signal to any process on the system. This is an IBM i (OS/400) version of that command, written in ILE RPG.
With this command, you can send a signal to any OS/400 job that is enabled to receive signals. For example:
KILL JOB(123456/QUSER/JOBNAME) SIGNAL(*TERM)
This sends the terminate (*TERM) signal to the IBM i job named in the JOB() parameter.
This software is open source, released under a modified BSD license. License details are given at the top of the KILLR4 RPG source code, available in the download.