Step 1
Remove the vinyl sash from the window. Most double-hung vinyl windows have a top and bottom sash that you can raise and lower or tilt in and out when you release two small tabs at the top of each sash. Release the tabs and tilt the top of the sash toward you. Twist the sash slightly by lifting up the left side of the sash. The sash will loosen from the window. Pull the sash out of the window cavity and place it flat on a table so that the interior side of the sash faces up.
Step 2
Locate the vinyl glazing stops that surround the edges of the glass. The glazing stop is a flat vinyl strip with a small lip that is tucked below the vinyl frame surrounding the sash.
Step 3
Place the flat-head screwdriver against the lip of the glazing stop on the right side. Lightly hammer the screwdriver head. The stop should slide out from under the frame. Continue removing all the stops around the sash frame.
Step 4
Run the utility knife along the bottom of the sash and approximately 8 inches up on both the right and left sides of the sash with the utility knife. Have a helper hold the sash to keep it from sliding off the table while you work. Cut the caulk at the location of the setting blocks, the small blocks located on the right and left side of the sash frame approximately halfway up the frame.
Step 5
Turn the sash around so the exterior side of the sash is facing you, and stand the sash upright on the table. Insert the blade of the utility knife between the glass and the exterior frame. Run the knife around the sash, cutting through the seal between the glass and the vinyl frame. Have your helper support the glass so that it does not pop out of the frame and fall.
Step 6
Push gently on the glass from the exterior side of the sash. Your helper -- wearing gloves -- can catch the glass while you slowly push the glass from the frame.