There are two screws that hold the Autopilot Tri-Sensor into the Autopilot plumbing manifold. Before you remove it, be sure to note the direction it is facing so you can put it back in the right way. You'll also unplug its wire from the controller. You can see the portion of the manual that talks about removing it on page 28 here: https://www.discountsaltpool.com/assets/doc/autopilot-digital-manual.pdf