If you have object level security switched on then you can use GRTOBJAUT and RVKOBJAUT to grant the authority to the 2 users and revoke the authority from *PUBLIC.
You can also do this by doing a WRKOBJ and option 2.
Use EDTOBJAUT (Edit Object Authority)
Set PUBLIC to *USE (or whatever level you desire)
and Set the two user profiles to *CHANGE or *ALL as appropriate.