CPIAD0B is “*SIGNON server job &3/&2/&1 processing request for user &4 on &5 in subsystem &6 in &7.”
You stop it by not running your *SIGNON server. Why would you not want network signons to be logged? Why would you want to remove evidence of network signons?
Technically, you can delete records from the QHST* files if you wish. I would never do it though. It removes audit information that might be critical in later analysis.
A RPG program can do the work. Make sure that you study the QHST* file carefully first. There are multiple records for most messages.