Carefully pry from the outside to remove. Don't twist the sash, this will break the glass. Find a good comfortable place to work, outdoors or in the garage. Use an old table or something solid to work on. Get as much light as you can reasonably get.
Bright sun is good.
Cover your work surface with newspaper or a good dropcloth. Preparing the window for glazing replacement. Put on your gloves, apron or old clothes, and respirator. Using a damp rag wipe down your sash to remove all dust. Check for visual damage to the wood.