what coach do you have?
on my rig it's one piece, middle "dimpled cap" is attached to the whole unit.
my simulated chrome wheel covers for the E450 come off gradually with a long, large, wide flat headed screwdriver (or any type of pry-bar with a wide flat head)
I start on the outside of the rim, pick any one side, pry off a bit, then move a few inches and pry some more.
a slow process 1/2 way around the rim usually releases the beast.