I have this same setup. When the EasyTouch panel is controlling my Intellichlor, the buttons on the Intellichlor do nothing, so there is something wrong with yours if you can still make adjustments via the two Intellichlor buttons. It may just be as simple as re-seating the connections of the Intellichlor on the EasyTouch circuitboard. It's not difficult to do, but if you're not comfortable working inside a computer (or with changing a light switch or plug on a wall), I would let a professional do it so you don't end up damaging the circuitboard or electrocuting yourself.
One thing you may want to check involves just using the buttons/software. I've noticed with my heat pump and Intellichlor systems, the settings don't always seem to "take" on the EasyTouch. Disabling and then enabling the function again is sometimes all it takes to correct problems that I've had in the past. It's almost if you do things too fast or slow or back out of the menu properly, the settings won't "take".
As for how to turn off your Intellichlor, the only way to do that is set it to 0% (either by way of the EasyTouch panel or on the Intellichlor itself) or (of course) simply turn off your pump. Turn it "off" at the EasyTouch panel isn't actually turning it off -- it just means the EasyTouch panel is no longer controller the Intellichlor, but the Intellichlor will continue to operate as it was set until you change those settings on the Intellichlor.
Actually, there is another way to immediately turn it "off", but it depends on what type of system you have. I have an EasyTouch panel, but do not have a spa (just a pool). If I want to instantly turn off the Intellichlor, all I have to do is put the EasyTouch in spa mode by pressing the V - Valve button on the wall panel. Because I do not have a spa, nothing really happens -- the pump continues to run, and because I don't have actuator valves installed to the spa valve ports on the EasyTouch panel, the intake and return is still from/to the pool. However, the EasyTouch now thinks I'm running the filter on the spa, so it reduces the Intellichlor output to (usually) 0%. If you turn up the Intellichlor production on the pool side, it bumps up the spa side in small increments, so it would usually be 3% production on the spa side. The highest chlorine production that can occur on the spa side is 20%. Anyway, mine is set to 0%, so when I press the Valve button on the EasyTouch panel, the Intellichlor is still running, but the element light turns off and no production lights are on (0%).
I found out about the spa/Intellichlor thing by accident. When I had my solar panels installed, the installer orphaned one of my actuator valves for my water features (I have a waterfall and two spitters). I called up Pentair and they told me that since I didn't have a spa that I could put the orphaned actuator into the spa intake or return valve ports, and just use the spa button to turn on that water feature. This seemed like a great solution to me until two days later I noticed from my routine water tests that I had very low chlorine in the water! That's because every time I was running my waterfall, the system thought it was in spa mode so the chlorine production went down to 0%......all day....oops.
Anyway, I would check the Intellichlor/EasyTouch connection yourself or have your installer come out and verify it. I wouldn't hesitate to contact Pentair tech support (their number should be on the bottom of the schematic on the door to your outside panel), as they've always been very helpful to me and talked me through plenty of things on the EasyTouch system -- from simple settings to some rewiring.
Good luck and let us know if and how you get it resolved.