There should be a black cap that screws off on the bar end side of the shifter. Take it off and then push the wire from the stem side toward the opening you just created. The head of the shifter cable should come out of that hole. Once the head is out, just grab it and pull the rest of the way out. Feed new cable through that hole when reinstalling. Sometimes, you have you shift gears a couple times to get the holes to line up to make it the easiest to get out and back in. Hope this helps.