PLC always overrides SRG which always overrides MFG constant. So the short answer is that you can't over ride the PLC directly. However, there are ways to use the program without using your PLC.
Are you sure you want to? Keep in mind that the STATISTICS that determine the PLC are extensive, take into account outliers, make multiple passes on the data and weigh the most recent data as the most important. But if for some reason you don't want to use it then any of the following approaches will work.
- Use a different PROCEDURE like STD PHACO2
- create a new Surgeon
- delete enough POST-OP data so that a PLC can no longer be calculated
- start over with an empty database.