So there are two schools of thought here: Ich management vs. ich eradication.
Ich management is my preferred method. I know I have ich in my tank, but I feed my fish high quality food and keep the parameters stable. Occasionally, one of my fish will show some signs of irritation, but its been a year and I haven't lost a fish. I feed frozen, seaweed pellets, and reef chili. My fish are fat, healthy, and extremely active. Never had any issues having ich in the tank.
Ich eradication is what it sounds like you are going for. Therefore, you will need to remove ALL fish from your display tank and allow it go fallow (fishless) for 90 days. You should continue to feed your tank so that your corals and inverts don't starve. You should treat your fish in the QT with copper or use the Tank Transfer Method ("TTM"). Copper is often a preferred method because the TTM leaves little room for error (you need to REALLY dry out the drained tank to make sure there are no ich parasites living in crevices) but it can be a non-starter for those who have fish that are especially sensitive to copper. You'll need to treat the fish with copper for at least 14 days (try to go as long as you can without causing too much stress to the fish) at 0.5 ppm copper. This SHOULD kill the parasites that come with the fish to the quarantine tank.
Keep the quarantine tank at least 10 feet away from the display tank and make sure you don't cross contaminate the equipment. Feed your fish well while in QT and keep your fingers crossed!