Hey Kardar, I cut mine a week ago, it is very easy, see the video in Glider post.
Regarding at which hight to cut the best is to put a 4 inch masking tape below your line of sight a go for a ride. if you dont feel confortable try to raise or lower the tape and try it agaoin riding. repeat as much as necessary to find your correct line of sight. Cutting the windshield - Harley Davidson Community