Check the ground (and other electrical connections) at the gauge cluster. My 1991 CRX Si was throwing code 17 almost daily until I found and fixed a broken ground wire at the gauge cluster.

If your talking about removing the speedo cable from the tranny, there's a little metal clip under the rubber boot on the cable; try gripping it through the boot and twisting the boot 90 degrees left or right (that should allow you to remove the speedo cable from the tranny).

Important note: Don't remove the bolt/clip next to the speedo cable on the transmission, it holds the speedo pinion gear in place, removing it could cause the gear to fall into the tranny, which would mean you have to pull the tranny and take it apart to put the pinion gear back in place.