You can decrease a stitch (abbreviated dec), which is really just subtracting a stitch, in a single crochet row. You decrease stitches in single crochet in the same places that you increase stitches — at the ends of the row or somewhere in the middle:
Insert your hook into the next stitch.
If you’re decreasing at the beginning of the row, insert your hook in the first stitch.
Yarn over (yo) and draw the yarn through the stitch.
You should have 2 loops remaining on your hook.
Insert your hook into the next stitch.
You’re continuing to work single crochets normally.
Yarn over (yo) and draw the yarn through the stitch.
You should have 3 loops on your hook.
Yarn over and draw the yarn through all 3 loops on your hook.
You’ve completed one single crochet stitch decrease.
Take a look at these symbols for single crochet stitch decrease.
Stitch diagrams use symbols to give you a pictorial description of the pattern design — and may or may not include written directions. These are the symbols for a single crochet decrease in crochet stitch diagrams.