Hi Joe
That's an issue I run into from time to time. You can't (I don't think) remove an ICAO from FSX. You can however reduce it to a single location dot in Airport Design Editor (ADE) and create a new airport at the same location with the new ICAO. I place the old ICAO "dot" at a starting position so if someone chooses the old name, which still shows up in the FSX airport list, they at least show up at a useful location.
In ADE there is also a "save as" choice under the "File" menu selection, you might try that. You can also go into the "Airport Properties" choice also under the "File" menu selection and change the ICAO, that might work. ADE is free, but I'll tell you now it can be habit forming as you realize how you can use it to make FSX airports more accurate.
Cheers, Neil
