Disable PAC Organization Cost Group in 12.1.3?

Client recently upgraded from 11.5.9 to 12.1.3.  All cost setups were performed in 11.5.9 and upgraded into R12.

Currently, there is one legal entity and one cost type defined.  The cost type is associated with multiple organization cost groups.  I understand that we cannot 'break' the association between a cost type and an organization cost group, but is it possible to eliminate an organization cost group from monthend processing? 

The client has re-organized, and many of the existing cost groups are no longer needed - yet they must still launch concurrent requests for them as part of the PAC period close process.  They would like to stop doing this.  They would also like to consolidate even further, perhaps into a single inventory organization, in part to streamline monthend close.