Pry against a wood scrap

Remove the chisel. The pry bar will give you leverage to pull the trim from the wall - at least, for this section. On most pieces of trim I had to repeat this process near each of the nails that held the trim to the wall. Make sure you pry against a piece of wood that will distribute the force along a larger section of the wall. Otherwise, the pry bar is likely to dent the wall in a spot not hidden by the trim.