I took mine to a tine shop and they spray soapy water and use this black trash bags. They spray the window and then place the bag on the tint. Leave the car in the sun for 15 minutes and the tint just peels off. This even worked on the back window however my defogger has not worked since I bought the car used in 95. I aksed him if this is the way they do it for working defoggers and said yeppers and that the lines do not stick if you give enough time for the glue to soften. Then he used ammonia to remove the remaining glue after the tint was removed.
Allen