Hi,  Just grab it with your fingers and pull it out.  If you feel you want to
lube it use some soapy water or in the extreme case Armeral.  I don't like
the PVC myself.  It doesn't last long in the ozone we have in the LA basin.
Better to replace the window rubber with the non-insert type glazing or for a
lower cost alternative, leave it out altogether or go to Home depot and fin a
drip irrigation 1/8" hose to press into the grove.  It costs almost nothing,
lasts forever, and looks great.
Cheers,
Kevin Dawson
87' Wolfsberg