To decrease a stitch, you need to work into two stitches without finishing them, then work them together. Here, a double crochet (see page 18) decrease is worked to demonstrate the method.
1 Insert the hook into the next stitch. Yarn over hook.
2 Draw a loop through the stitch, but do not finish the double crochet stitch as usual.
3 Insert the hook into the next stitch. Yarn over hook.
4 Draw the loop through the stitch only, there should be three loops on hook in total. Yarn over hook.
5 Draw the loop through all the loops on the hook, drawing two stitches together. One stitch decreased.