Cut yarn three times the length of the knitting you need to bind off, thread it onto a tapestry needle

Step 1: from left to right, insert the tapestry needle purlwise (from right to left) through first two stitches) and pull the yarn through

Step 2: insert the needle knitwise(from left to right) through the first stitch, pull the yarn through and slip this stitch off your needle.

Rep steps 1 and 2.