Cut the outer cable covering with wire cutters or scissors of both cables and be careful not to cut the wires themselves.

Pull off the piece of cover that you've separated from the rest. You should be left with four exposed individual wires.

There should be four wires, and occasionally a piece of string too. If there are fewer wires, then you've clipped one off, and you need to start over.

If there are more than 4 wires, you probably have a USB 3.0 cable. In this case, make sure that whatever wires you'll be reconnecting are both USB 3.0.