Ventilate the area well and put on a face mask and goggles to protect your eyes. Ammonia can be caustic and breathing the fumes can be dangerous.
Pour a small amount of undiluted ammonia into a spray bottle to make application easier.
Spray ammonia directly onto the adhesive. Allow the ammonia to work for a few seconds before scrubbing.
Scrub the adhesive with fine-grain steel wool. Be careful not to press too hard, but scrub quickly while the ammonia is still wet.
Wipe away the adhesive residue and ammonia with a paper towel and assess the window. If any adhesive residue is still attached to the window, repeat the ammonia and scrubbing until it is removed.