What is the easiest way to shrink a back window film?

Method 1: Use a dryer sheet, rub an “H” pattern with a damp sponge and then dry shrink.   Method 2: For a non-toxic method, use a soap bar on a damp towel, and then blow it dry, and then dry shrink.   Method 3: In place of dryer sheets or soap, use a heat spray.