Place drop cloths or towels underneath the window to catch drips and on nearby furnishings to protect them.
Cut a drop sheet or garbage bag with scissors so it's the approximate dimensions of the window glass.
Mix up a soapy solution in a spray bottle. Pour 2 tsp. of liquid soap into the bottle and fill the bottle with water. Shake it gently to mix the ingredients.
Spray the window film generously with the soapy water. Place the cut sheet or bag on top of the film so it's completely covered. Press it down into place. Spray the top covering with the soapy water until it's wet. Allow the window film to soak undisturbed overnight.
Remove the drop sheet or garbage bag from the window. Pick the top corners of the window film loose with your fingernail. Grab the corners and slowly pull the film down and away from the glass.
Spray the window glass with the soapy solution to soften any leftover adhesive. Use a stainless steel, single-edge razor blade or a wide blade scraper to scrape the glass clean. Hold the blade flat against the glass and apply equal pressure. Spray the glass as needed to keep it wet so the blades don't scratch the glass.
Spray the window with cleaner. Use a lint-free cloth to wipe it clean.