why doesn't NWC have multiple staff selection, if it did, deleting extra repeat measures from an imported MIDI file would be much easier
You could implement a simple user tool that took the starting and ending measure numbers that you want to delete as input parameters, and echoed back everything in the staff but those measures. Granted you would have to do it for each staff, but it would be much simpler than doing it by hand. The only tricky part would be counting the measures correctly (i.e., make sure there is at least one note, chord, restchord or rest in a measure before you count it).