Use a seam ripper to cut through all the buttonhole stitches on the back of the garment, including the bar tacks at the top and bottom. On the front of the garment, use the seam ripper to gently pull out the top thread (it should pull off in one piece), taking most of the bottom stitches with it.
What is a hand-worked buttonhole? … Just like with a machine-sewn buttonhole, first you mark where you want the opening to be. Instead of sewing first and cutting second, reverse the order. Cut the opening first, then the threads are sewn over the raw edge of the fabric, wrapping the fabric with the thread.
Threads’ seamstress Norma Bucko distinguishes between the stitches by remembering that, in the blanket stitch, the needle point goes down into the fabric from the right side. In the buttonhole stitch, the needle’s point comes up through the fabric from the wrong side.
A bound buttonhole is one which has its raw edges encased by pieces of fabric or trim instead of stitches. A keyhole buttonhole is a special case of a thread-finished buttonhole that has a round hole at the end of the buttonhole slit, reinforced with a fan-shaped array of stitches.