Score around the seams of the wooden trim molding surrounding the sliding window on the interior side using an utility knife. Scoring the seam will break the paint seal on the trim molding so that it will pry up easier.
Start at one end of each length of trim molding and slide the edge of a trim molding flat bar under the molding and pry up gently. Take your time and work each length of molding up. Remove each piece of trim molding from the window opening.
Remove any stray nails that may have been left in the window frame using a nail puller. Be careful not to dent the wood surrounding the window.
Pivot the sliding window, top end first, out of the window opening and carefully remove it from the window opening. Rest the window carefully on a work surface.