The real world doesn't often fit digital models very well and thus there isn't a sure way to separate one part of the signal from another part.
Once something is mixed in to a signal, it's part of the signal.
The old adage crap in, crap out still greatly applies to audio. You can reduce it some, but it is unlikely to be able to be removed entirely and may well produce artifacts in your audio in the process. Once it is there, particularly if it is really loud, there isn't a whole lot you can do about it that will result in satisfactory audio. The use of a wind cover can help break up the wind and prevent it from interfering with a recording. The best bet is to avoid getting it on the recording.
