There are many reasons that you might want to remove the ribbing on a finished jumper. You may want to lengthen it, shorten it, knit the ribbing in a different colour, stitch, or on a different needle size (and many other reasons besides!)

I recently had to do this on a jumper I made for my Dad, so I thought I'd document the process in case anyone else needed to do it.

My jumper was knit in the round, but the process is the same for flat knitting. If you have sewn the side seams you will need to unpick the seams first.

Thread a needle with a doubled piece of scrap yarn the same thickness as your knitting. Thread it through the row of stitches that you want to begin knitting at later on, making sure that the right hand "leg" of each stitch is on the front of your darning needle. This way all the stitches will be the correct way round when you slip them onto your knitting needle later on.

Carefully cut the stitches above the row you have threaded with yarn. If you're nervous about cutting the stitches you want to knit with you can cut the stitches several rows above.

Tallguy's Tip: I prefer to snip one stitch in the row, near (but not at) the edge, and pull out the row. The stitches neatly fall away, leaving you with ribbing to knit on, and the body of the sweater to knit on as well (or to rip out, if that is what you want)! Also, you don't end up with any messy bits at all and you won't have wasted any of that precious yarn.