Rubber and plastic boot between door and jamb.

I've troubleshot the problem with the unlock button on drivers side door not
working, the lock button works.  Removing the door panel and jumping the
connection for unlock, nothing happens.  I suspect a broken wire inside the
boot, since the car is 21 years old.  Here's the question.  I've remove total
rubber boots before but this setup is different.  The top portion is hard plastic
with a nut on top.  The bottom is typical rubber boot attached to hard plastic
via what appears to be a zip tie around it.  How does one remove the hard  
plastic shroud with the nut on top to give access to the wires.