You are having a time with this! A quick search suggests:
->If the scorch mark is fresh, soak it immediately in cold water for at least 24 hours. Often, this will remove the marks. If not, continue with the next step.
->Wet the scorch mark with hydrogen peroxide. Remember to spot test first. Peroxide may fade some fabrics and/or colors. Wet the clean white cloth with peroxide, then place it over the scorched fabric. Iron lightly.
Repeat, keeping the cloth moist with peroxide, until the stain is gone or until you no longer see improvement.
->As an alternative, rinse with white vinegar then water and repeat until the stain is gone (or you no longer see improvement).
->One more trick is to cover the burn mark with lemon juice and lay it out in the sun. This causes a natural bleaching effect, but it may fade fabrics, so spot test first.
Good luck!