First you should create a real number parameter called something like PART_DIAMETER and attach it to the diameter using relations. In relations you would either type PART_DIAMETER=dxxx or dxxx=PART_DIAMETER (you will find the dxxx value by clicking on the extrude sketch while in relations), depending on whether you want to control the diameter by changing the parameter or have the parameter change based on whatever value you put in the extrude sketch.
After that you open Pro-Program, locate the larger bolt hole pattern and type IF PART_DIAMETER<=5500 right before the ADD FEATURE (initial number xx) text that Creo has generated. Finally you locate END ADD and type in END IF after that. Make sure you get both the hole and the pattern you want to suppress in between the IF statement and END IF.
It should look something like this:
IF PART_DIAMETER<=5500
ADD FEATURE (initial number xx)
feature ID, parents, dimensions etc.
END ADD
END IF