It is easy to remove the tint, just kinda messy.
They've always proposed removing the defrost lines 'cause they did not want to wait or just do it as easy as possible for them.
DO AN INTERNET SEARCH.... you may find pics and other tips. Basically, I recently did it by following what I've typed below. I removed mine and am getting ready to take it to get re-tinted. I've done 3 MKIIIs and 1 MKIV following the basic directions below. This is exactly what they'd do, if they wanted to spend extra time at the tint shop.
Make sure the back window is directly facing the Sun. It would be best to have someone else help, since the trick is getting the plastic to stick, while trying to keep other ends from falling. This is wher an extra set of hands is essential.
Get a black plastic bag, cut it open so that you only have one wide layer. Spray the window with windex or anything containing ALOT of ammonia. Best to get some straight ammonia and maybe slightly dilute. Either way, spray on the window, place the plastic on it to where it sticks and keeps the moisture pushed up against the tint. Shut the hatch, letting the extra plastic stick out of the sides and be held in place by the hatch seal. Go inside and make sure to push any plastic back onto the tint, wherever it may have dropped as you closed the hatch.
Anyways, do not use a razor, except to help lift the tint after about 30 minutes in good, direct Sunlight. I would actually re-spray (not completely removing the plastic) every 20 minutes for an hour. Just pull up a corner at a time to respray.
After the tint's good and warm/hot for awhile, try using the razor to lift a corner of the tint and pulling it away in one complete sheet (keeping the plastic still attached so that the liquid does not dry up).
The 1st time I did this, the film did not lift off in one piece and I had to put the plastic back on and try removing the remaining "piece-by-piece." Still when I did it this way, it only took about 90 minutes total and I kept the defrost.