Here is what you need to do, and yes, it's a lot of work.
You have introduced ick into the tank already by adding the infected fish. Removing the fish and returning it will not help as the ick is almost certainly in the tank. Ick works in 3 stages. When the parasites drop from the fish, they lay dormant in the tank until they hatch, releasing free swimming parasites. These parasites find a fish, and burrow into the skin, forming what we call ick. The cycle then continues.
The only way to kill the ick, is in the free swimming stage. The absolute best way is copper but you need to be very careful with it's dose strength, espcially around angels. Also, you cannot dose this in a reef tank, or you will kill your corals and any nitrifying bacteria. Most other reef safe products either do not kill the ick, or are not reef safe at all.
What you need to do is remove ALL of you fish. Snails and Shrimp etc are ok to remain in the main tank. Your tank must then remain FALLOW for 6 weeks.
(No fish in it at all) The parasite will die off due to not having an intermediate host to complete it's cycle.
All of your fish should now be in a quarantine tank. (The bigger the better) with nothing but some PVC for hiding. Dose the Copper at the recomended amount. (Copper only needs to be dosed once/not daily). Raise the temp to 84. (This speeds up the parasite cycle.)
Do not add live rock or a biological filter as the copper will kill it. Keep a couple of strong powerheads in the tank to keep the flow up.
Perhaps you should list the fish you have so we can verify that they will be safe from the Copper as it can be deady to some species.
You will then need to do the following daily.
-Add top off RO water to the quarantine tank.
-Monitor Ammonia and Nitrites in the quarantine tank.
-Change a certain volume of water based on fish volume/ammonia levels (I change 25-30% daily.) Remember to add the appropriate amount of copper the the change water. (Not the RO top off water otherwise you will be raising the copper level as it does not evaporate)
Leave the copper in the quarantine tank for 7 to 10 days depending on the look of the fish. After this the ick should be gone. Do a 50% water change and add carbon and some filtration device to remove the remaining Copper. I add Purigen as well to help control the Ammonia and Nitrite until the filter can get the bacteria going. Perhaps even add one of those Bacteria jump starts to get the tank cycling faster.
Thats it. Easy!
Now don't you wish you had quarantined
Honestly, this is the only way to remove ick from your tank. Good Luck.