Window tinting. Removing sprayed mark on the glass

New tinting...better visible light, light reflected , UV Rays reject and Heat reject.
But there's a marking on the windows / glass... :(
Perhaps the old owner over sprayed it, made a marking on the glass...

The mark on the external glass

 So...I've used some WD-40 to lubricate it then scrapped the marking with sharp knife.
 Do it nice n easy.

RED : Before cleaning  GREEN : After cleaning