I'm asking for my cousin in Hong Kong, whose little children stuck this window sticker onto the glass. We read How do I remove the gluey residue left by gaffer tape on glass, https://diy.stackexchange.com/a/30948, Removing Tuck Tape from an unfinished window frame, but nothing works! Please see the picture with my labels below.
We tried vegetable oil, dishwash detergent, rubbing (isopropyl) alcohol, and vinegar. The only solution is to use our nails to tear off a litte piece of the tape, a tiny piece by tiny piece. Please help! Thanks!