How to shorten a T-shirt in street dance: First, you need to take apart all the cuffs on both sides. Measure the length of your arm and work out the length you need to cut. Measure the excess length and mark it. Then fold the extra part into one piece and mark it. Take off your clothes and fold more clothes according to the marks. Sew cuffs with a sewing machine. You can sew up the folded part with a sewing machine. Iron the clothes that have just been mended.