How do you remove plastic fixings to remove glazing panel?

by fixings do you mean the knock on beads? if so it depends on the age of your window, if your window is old it will be externally beaded, to remove these beads you first have to go inside and remove the black rubber gasket, this enables you to remove the beads from the outside by teasing the beads away from the frame.
if your window is new it will be internally beaded and you can just tease the beads away from the frame, to tease the beads in both instances use a clean metal wallpaper scraper in between the beads and frame taking care not to damage them.

scott.
April 2012