How to remove manual journal posting functionality from General Accounting Manager role?

Hi Everyone,

We would like to remove the functionality to post manual journals from the General Accounting Manager role. I've found some articles indicating that the Journal Management duty role should be copied, then remove posting privilege from this, and then assign the custom Journal Management duty role to the main role.

I've tried this, however when I try to add the custom duty role, I receive an error stating that the inherited roles already form part of the main role. I also see that that some of the security policies related to posting cannot be deleted (I think this is part of what is causing the issue).