1. To remove the shifter, cut off the end of the shifter cable and release it from the derailleur.
2. After removing the brake lever, throttle, and brake lever (refer to the brake lever, throttle, and brake lever replacement guide), unscrew the bolt from below the shifter, then slide it out and remove the shifter cable with the housing.
3. When installing a new shifter, insert the cable into the groove and push it in.