Hi,
Why you want to stop automatic creation of inforecord for a specific PO type?
You can stop the automatic creation of inforecord with OMET ( default value for purchasing) & OMZT and SU01 for specific users.
Instead of specific PO type - you can go for specific users.
Go for creation PO from Contract where no inforecord required by assigning of default value for purchasing in Parameter ID EVO in SU01 t.code for few users
Go for creation PO from PR where inforecord required where no assignment required of default value for in Parameter ID EVO in SU01 t.code for specific users
Regards,
Biju K