Ok. You should be able to bind off simply by knitting the middle stitch, knit the stitch directly after it, then pass the middle stitch back over the second knit stitch and off the needle. I assume that you are probably doing something on the other side of the bind off in order to get that stitch back. If its a scarf it probably wants you to maintain the number of stitches while doing the bind off, which means that there is going to be an increase somewhere else to make up for the loss of that bind off stitch.
You can't do this with a decrease. The purpose of the bind off is that if you do it in the same place over and over again its going to cause the slit, it makes a gap in the fabric. If you use a decrease you are only going to reduce the number of stitches while keeping the stitches linked together. By using the bind off, you are going to break that link and create the slit.