While it might seem as though the zipper has almost always been around to fasten pants and close coats, it's a fairly modern invention, dating back to 1918. Gideon Sundback is the inventor of the item and while it has served mankind very well, not everyone prefers to use the series of tight, metal interlocking teeth on their clothing. Kids can prick their fingers on zippers, struggle with fastening them and keeping them fastened. Just because a coat comes with a zipper does not mean you have to use it. Instead, it might be more user-friendly to replace the zipper with Velcro.
Lay your coat out in front of you on a flat work surface. Starting at the bottom of the zipper, gently tear out the seam that secures one end of the zipper in place. Repeat on the other side of the jacket.
Continue tearing out the zipper seams until you can pull the sides of the zipper out from the jacket. Yank out or trim away any loose threads with a pair of scissors.
Fold the edges of each side of the fabric inwards 1/4 inch to create a new hem. Pin them in place and sew a simple running stitch down the length of each side to secure it.
Put on the jacket and mark with a piece of chalk where you want the Velcro straps to go. Take off the jacket and pin each end of your Velcro strap to the appropriate chalk mark. You may need to trim some of your Velcro straps down if they're too long or you want a snugger fit.
Sew around the perimeter of each Velcro strap, creating tiny, tight stitches with your sewing machine.